OP, where in Canada are you (if you don't mind me asking)? I'm in Southern Ontario and know a few mice and rat breeders - much better and cheaper than the chain pet stores like Petsmart!

If you aren't down this end, I'd advise you to do some deep searching in your area! Sometimes breeders do mice/rat breeding on the side, apart from their own stock. You can always post an ad on Kijiji as well