I think craiglist is available for Canada... check there!
You would also check second hand stores, I've seen tanks at Goodwill for $8.
Most members here are in the US and anything shipped to you will be very expensive.
Larger critter keepers (3 gallon-5gallon) can be great permanent home for your betta and try to ask your friends or your family to see if they know someone that sell the tanks cheaper or giving the tanks away.
oh man! if you were in the US i'd send you an empty 10 (nothing but the tank) for like, 15 bucks plus shipping. Walmart has 10 gallon kits for like, 30 here so they might be similarly priced or a little more up in Canada? Also empty tanks for 13 bucks here.