As a fellow Canadian, one of the most frustrating things about ordering from US stores online and shipping internationally are the dreaded surprise bills that you get upon receipt.
You could buying something for $100 and your courier will slap you with a bill for another $50. Even worse, sometimes the customs fees are equal to the value of what you bought.
If you've read stories on CBC, and covered by other news outlets, the couriers control the entire workflow of how your packages get from the United States to Canada.
HOW TO STOP PAYING CUSTOMS FEES TO COURIER COMPANIES
This is the unavoidable charge. For most things that you ship into Canada, they'll be taxed according to your province's rate. In Ontario's case, that's a 13% HST.
Duty is a bit more complicated because it depends on the type of goods you bought and where they came from or where they were made in. Officially, it means having a good understanding of HS Codes and Trade Agreements.
It's called “self-clearing”. I had this confused with “pre-clearing” at one point but yes, the official term for what you'll be doing is to self-clearing the package instead of letting the your courier do it for you.