Not sure what you mean by 'hidden charges', - haha, well, if they were 'hidden' nobody would tell you anyway, haha.:^O
When you see a listing, you will notice the item price as well as a shipping charge. If it is a Canadian business seller you may be required to pay tax according to your province. All this is clearly discernible from the listing. If you are buying in a currency other than Canadian dollars, there is a currency conversion fee of about 2.5%. The exact amount you pay depends on the daily fluctuations of the Canadian dollar in relation to other currencies. So if you are buying in US$, the amount you pay will be a teeny pinch more than what it shows at checkout, but not much.
And of course, if you buy something from outside Canada, any item with a declared value over $20 may have duties and taxes applied before you can get your hands on it. Canada Post charges $8.50 to process the paperwork, and couriers charge a whole lot more so avoid them if you can.
So nothing hidden, - not if you know where to look. 😉
