There's an entire thread devoted to CBSA Importation and collection of duty here.
Shipping is never calculated into the value fo the shipment. CBSA isn't stupid, they know what our stuff is worth and the whole "gift" thing is just a way around duty fees if it's from a company. They know the game very well. It doesn't matter what you tell whoever to declare the value at, if CBSA think it's worth more, they'll just bill you more for it.
For the record, after importing goods for the better part of a decade (not just airsoft goods either), I have never, ever, been charged duty. GST yes, duty, never. And don't forget CBSA's $5 fee (I've occassionally been charged $8) if they decide to "look" at your parcel, on top of GST if they decide to charge you for that.