The thing is tire pricing in Canada is a rip off. For example, I recently purchased a set of Michelin Pilot Super Sports. The best price from a Canadian retailer was $1650 (not including mounting and balancing). I ordered them out of the US for a total landed cost of just under $1300. That savings is helping me to get my wheels refinished.
Same thing for competition tires. I get R-compounds about $300 - $400 cheaper out of the US.