While Process for valuing items for customs purposes at the Canadian border discusses how an item is valued and one of the answers has
if you recently bought it, determining the value is simple: look on the receipt, perform a currency conversion, and you're done.
But if I bought it online, does shipping matter or not? I am looking at a 24 hours absence visiting a friend and the item is 140 USD (~190 CAD) but the shipping is 30 USD (~40 CAD) so shipping pushes it over the 200 CAD exemption.