I have two Canadian Tire stores nearby (in Richmond, B.C.); one always has a full stock of CO
2 cartridges (5/25/50-packs), the other doesn't seem to carry them at all. Which is odd, as they both sell CO
2-based pellet guns & softair/crapsoft.
I find the pricing frustrating; $8 for 5, $23 for 25, or $30 for 50. Hell of a markup if you just want a few cartridges. (Or, I suppose, a hell of a markdown if you want lots.)