I don't know about Ontario, but the CAA in Alberta also sells them in store. The online purchase is actually charged in US funds assuming an exchange rate of 79¢, but CAA charges the face value in Canadian funds. Online is $44.20 USD, and CAA is $57.46 CAD. You'd have to figure out what the current exchange rate is to see which is the better deal.
SeaWorld/Busch Gardens is $60 CAD per adult and $50 per child - booked thru any travel agency. Holiday House is the name of the tour operator they buy it through. Good deal.
Universal has a deal as well but you have to buy 2 parks/3 days to get the rate. I believe it is around $148 per adult. Also thru Holiday House.