Items over $20 in value are subject to duties and taxes. Depending what the item is, something made in China could have both. Duties are not huge, usually around 10-13%, but maybe as low as 5% or as high as 18%. Again, it depends what it is.
Tax you would pay according to your province, the same as buying things locally. And items from China are usually sent by the post, so Canada Post charges $8.50 for processing if the items are assessed. They are not always, and often just show up at the door. But always be prepared to pay, just in case.
So what you 'could' be expected to pay, - start with the item price, tax on that; plus (possible) duty, tax on that; $8.50 processing, tax on that. Add it up and it's the most you'll have to pay.
Avoid couriers if and when you can because they charge big brokerage fees, so that $10 UPS to Canada sounds cheap until you get the whopper at the door. But when buying from outside the country, you are an importer, and importers must expect to pay charges. In town these are built into the prices, and taxes you pay at the checkout. Same thing, really.
Have a look at the following link about importing by mail if you like:
http://www.cbsa-asfc.gc.ca/import/postal-postale/duty-droits-eng.html
