you just got hit with FedEx's brokerage fees. It's not a tax, or duty or import fee. FedEx charges you some random, inflated amount for their broker to clear your package through customs. It's usually % of the declared value of the package.
UPS is just as bad.

For cross-border shopping (mainly US->Canada) i always chose the "regular mail" (USPS/Canada Post) option. The brokerage fees are much cheaper, and sometimes nonexsistent.