You can be charged tax or duty and a handling fee when you import an item that cost more than $20. But usually, if an item is sent by mail rather than by courier, there are rarely any charges on a purchase unless it is more than $100. Then, the charge might be the amount of gst/pst due and a $9.95 handling fee from Canada Post. There really is no guarantee that you won't be charged but it does seem to be the norm.