As someone already mentioned, if possible Canada Post is the best option. It's not necessarily the fastest (UPS or FedEx are faster) but most importantly IF they charge any customs, the BROKERAGE FEE is a flat $10 rate, no matter what the item. Most of the time, depending on the item, there isn't a fee. But if/when it gets charged then they only charge $10.
I have bought stuff from the USA and had it shipped to Canada via FedEx or UPS, and the brokerage fees were outrageous, close to $100. Never did that again.