We ship a lot of packages to Canada every week so are very familiar with the process.
It depends on the amount of the purchase. You can be responsible for GST, Brokerage Fees, and Duties if your country chooses to impose them.
As an exporter, I am required to state the actual value you paid for the goods on the customs form, or face fines if I'm caught cheating on it, so what I do is to declare the actual value of your purchase, minus any discounts you are given, i.e. the actual amount you paid after any discount.
Asking an exporter to lie about the declared value on the customs form, or asking them to declare the goods as a gift is asking them to break the law and face possible consequences. No exporter with any brains will do either, IMO.
You can however affect the amount you have to pay by making sure your exporter (the person who sends you the goods) uses the postal service (USPS) to ship rather than UPS or another shipper. UPS especially seems always to charge brokerage fees on cross-border shipments, while USPS/Canada Post seem to mostly skip those except on very large orders, and even then they are minimal. UPS also seems to take a lot longer to clear customs.