It's expensive bringing the stuff back into B.C. (not sure what it's like for other provinces but you're in B.C.) Customs used to be quite lenient (once declared 3 magnums + 1 regular bottle of champagne carried by 2 persons and were let through) but an agent told me last year that they had just really started enforcing tax collection on excess of allowance. Tried bringing in 3 bottles of wine last year in excess (between 2 of us) and the tax on an amenity freebie and 3 Buck Chuck was about C$5 a bottle. It isn't federal taxes but the B.C. taxes and fees that are really high. Figure 100% for cheap wines (fixed per bottle B.C. fees). Probably 50% range for more expensive stuff.

Best way to bring wine back duty free is to be posted out of the country as a federal government employee and bring it home as part of your possessions.