Canada Customs allows a personal exemption of about approx. $40-$50 for imported item via mail. There is NO duty on action figures/toys.
If you have to pay a fee, its for GST/PST on the total value of the shipment including the shipping costs. The total amount shouldn't be more than about 15%, or $15 of $100 value.
Customs does not always assign this fee, and they are less likely to if the import is, say, just 2 or 3 carded figures. You are more likely to see the added fee if the items are very expensive or if its a case of figures because the oft-assumption is that the items may be for re-sale.
If you use a courier, you'll very likely get assigned brokerage fees, for the intermediary at the border who "handles" and "guarantees" the package for Customs, to allow it into the country. Usually the brokers fee doesn't even appear itself until later, when you receive the separate bill for it, but it can be reflected on the parcel when it arrives and , I believe, is calculated into the value for declaration which can bump up the amount that much more.