I'm located in London and thinking to get a kitten (or two). (Assuming my landlord does not object.)
I have about 150 GBP per month budget. Is this sufficient for a British-short-hair? Is this sufficient for a mixed breed kittens? (I am just checking the budget so I can plan my finances. I do not have a tight budget if the cat is sick for example and can handle ad-hoc expenses if needed)
Update: Landlord said no to getting any pets.
As far as I know, breed is not a strong indicator of what to expect for cost when it comes to cats; their general health is a larger indicator, and something that can't always be determined as kittens. There are, of course, some good ways to estimate what you might pay to own one (or more) cats. I'll include some price estimates; because I am located in the US, these estimates will be in USD and based off the pricing on the online retailer Chewy.
Pet Rent: This is the very first thing to check before you go any farther. Will your landlord allow you to have a pet? If yes, what (if anything) extra will you be charged? It's not uncommon to have an additional monthly fee as well as an additional deposit, commonly assessed per pet. In my home state, an article from 2019 cites an "average pet deposit [of] $185 per animal, with an average monthly pet rent of $25 [each]." Cats and small dogs will typically land on the lower end of pet rent scales, while larger dogs can go much higher.
Adoption Fees: These will vary by area, rescue, and age of the cat. Kittens typically have higher adoption fees than senior (the next most commonly adopted range) or adult cats. Speaking from personal experience, my two older cats were $150 each, and the younger was $175 (though I paid $180, giving the extra to the rescue as a donation). These fees cover the cost of food and veterinary care prior to your adoption of the pet, and frequently do not cover the full cost.
Veterinary Fees: Just like you need to see a doctor regularly, your cats will need to see a vet on a regular basis, both for vaccinations and for regular health assessments. You'll want to get them spayed or neutered, if they didn't come to you that way; these prices will again vary by area, as well as whether you use a standard, premium, or low cost clinic for the service. The amount you pay can flex as well based on whether the clinic you choose takes monthly payments or offers service packages; I personally use a service that costs around $35 per cat per month, but covers all office visits, vaccinations, and several other routine procedures. All of this is outside of any "extra" fees when a cat gets sick and needs additional treatment.
Basic Supplies: There's a few things you'll have to have: an appropriate food bowl for each cat, at least one water bowl, at least one litterbox (recommendations are for one per cat plus one extra), a litter scoop and a good way to dispose of the litter. Prices on these can range; a basic melamine bowl from Chewy goes for about $2; "whisker fatigue" bowls (lower bowls that are more comfortable for cats to use) start around $3. As you start getting into fancier styles (elevated, ceramic or metal, etc.) the price can reach around $25 per bowl. A water bowl will start around the same, but many cats prefer fountains, which will range from around $20 for the most basic plastic styles, to $100 for fancier styles. Litter boxes, again, will range in price, with your most basic small litter pan on Chewy at around $5 (much too small for an adult cat) up to $100 for more elaborate standard pans, and even higher for automatic cleaning options. These can be considered "semi-one time purchase" options--you may need to try different bowls, litter boxes, or waste management systems before you find the one that suits both you and your cats. You'll still need to cover all of these up front, after which experience will start to guide you on what to replace with better options.
Consumable supplies: Here's where your monthly costs will start to come in. Your cats will need food, litter, and treats (useful for enrichment, still to come). Kittens will need extra calories; my personal approach is to free-feed them with a kitten formula kibble, as well as scheduled feedings with wet food; I transition my cats to an all-wet diet as adults, as it tends to be better for weight management and urinary tract health. A basic bag of low-end kitten kibble is about $6 for three pounds; a good brand will start around $10 for a similar size. Wet food for kittens starts out around $7 for a case of six-3 oz cans (which is not a lot of food!), and again goes up from there. My adult cats get about 160-180 kCal/day, which with their current brand of food is about 4-5 oz of wet food per day. If you choose to get into freeze-dried or raw/fresh made options, the price can go up even farther; mine, personally, have rejected these types of diets. Litter, similarly, varies in price based on type and material; basic non-clumping litter is about $5 for a 7 lb bag, but you probably will want one that clumps for easier clean-up. A basic box of clumping litter starts around $10 for 14 lbs. Avoid scented options (other than "cat attract" type options), as the scents can be a turn-off to the cats and lead to litter box avoidance issues. And like everything else, treats can vary in price and quality. A basic bag of treats runs around $3, give or take; freeze dried options or "premium" ones will go higher.
Enrichment: This is where people tend to let their cats down; many tales of cats who "are miserable indoors" or "just won't behave" are ultimately tales of cats who lack enrichment options. Proper enrichment isn't just a stuffed mouse or a ball with a bell in it--you need a range of options to cover multiple play styles and behavioral needs. Yes, do get the stuffed mouse and the ball with the bell in it; also get stuffed balls, pompons, crinkle balls, kicker toys, catnip plush, crinkle plush, real fur toys, coil/spring style toys, "trapped ball" toys (tracks and boxes), and other types in the self-directed play range. Your cats will decide what they like and don't like, and you can continue to purchase in the styles they gravitate toward. Thankfully, most of these toys can be found fairly inexpensively, often for $1 or so, though with very cheap ones you'll want to make sure they can't easily be pulled apart--and always remove damaged toys from play. Additionally, get some wand toys (a toy attached to a stick with a string) for interactive play--keep these put away when you aren't using them. Lasers can be a good option here too, though some controversy exists around whether they're enriching or frustrating to cats. Mine, personally, do enjoy them and don't find them frustrating; treats can be used to reduce the "frustration" as well by giving them a prize. Treat dispenser balls and puzzle toys can be good for directing energy and giving them a reward for their activities; treats can also be used for direct enrichment by tossing them to the cats to be chased or using them to teach simple tricks. Beyond toys, you also need furniture. Start with scratching surfaces--these aren't just "scratching posts," but a variety of textures and orientations. Mine have choices of carpet, sisal (rope), and cardboard for materials, and flat, angled, and vertical for orientations, and they use all of them, each with their own preferences. Scratching surfaces will run you around $10 and up. You'll also want climbing surfaces, also called "cat trees." Cats naturally are inclined toward climbing, napping, and perching in elevated spaces; these also give them great locations to watch both interior and exterior (if placed near a window) spaces, and with multiple kittens, a great place to chase each other around. These typically include scratching surfaces, which can help cover those needs as well. A small cat tree typically will start around $40 and go up from there; test for stability when purchasing taller ones to be sure they won't be able to tip it over. Additionally, cats like hiding spaces; pop up cat tents, "condos," and even plain cardboard boxes can be great for these options. I even have some inserts for Ikea's Kallax shelf that are designed for cats to tuck themselves into. Hiding spaces are the most budget-friendly option, as they start at free when you cut a door in a shipping box. Many cat trees also include condos as part of the design; a good cat tree can easily cover many enrichment needs.
Miscellaneous: There are some additional things you'll want to consider beyond the categories above. Do you want collars for your cats? You'll want to be sure to get a good quality, breakaway collar--cats can become hung up on their collars, as they tend to sneak into narrow spots where they can become stuck, so a collar that pops off easily can be the difference between life and death for that cat. Prices here will start around $7. You should consider some enzymatic pet cleaner; accidents happen, and regular household cleaners aren't generally sufficient for cleaning pet messes. These will run around $5 and up. Do you want to leash-train the cats? You'll need harnesses and leashes for them, usually around $20/set. (Note: never leave a cat unattended in a harness!)
To summarize, you're looking at an initial cost starting at a bare minimum of around $30/cat, assuming you have no pet deposit, and somehow get a "free" cat that's fully vetted already. This is extremely unlikely to happen, making the more likely initial minimum around $200/cat (again, assuming no pet deposit). Add to this a bare minimum monthly cost of around $25/cat for low-grade food and cheap litter, with no pet rent or vet costs factored in; this cost goes up with better quality food (which brings vet costs down in turn), and may shift depending on the calorie needs of the cats and how fast they go through food and litter as a result. None of these estimates include veterinary fees or any kind of veterinary coverage plan; with a coverage plan, you can assume another $20+/cat per month.
Lastly, note that while many of these costs are less frequent than others (I haven't bought a litterbox in years!), by adopting a cat you are committing to these costs for 15-20 years.
One thing to add to Allison C's excellent answer is insurance.
Pets, like people, get sick. Unlike people, there is typically no government help for healthcare costs. Think of all the scary medical bills uninsured people in certain countries may face and you get the idea. Not quite as high, but still scary if they are unplanned expenses you can't afford.
Insurance is a way to remedy that, and it works similar to health insurance in countries that use it. You pay a monthly/annual fee and they cover the vet bills. The monthly amount depends on the age of the pet (older is more expensive) and their pre-existing conditions (which they may or may not cover you for). There is typically a coverage limit and an excess that you have to pay for each claim, and the premium will go up after a claim.
As an example, for our middle aged cat it was about £15 a month, and it went up to about £22 a month when they became 'senior' (it might have been age 8, but it varies by insurance company). When the other cat had to go to hospital for a few days the bill was about £1000, which was covered by insurance. The bill could have been a lot higher if the condition was more complicated.
As always, insurance is a risk calculation. If we had put £22 every month into a savings account since the cat was small, maybe it would have paid the vet bills with money to spare. But there's always a risk the bill would be higher.
