Allen @ Simpy Tire is one of the very cheapest in Toronto:
http://www.simplytire.com/
His price for install is also very cheap and includes Hunter Road Force Balancing. He'll beat Tire Rack's "Shipped to Canada and installed" price EVERY time.
That being said, I just bought (and installed) my Michelin PSS from Dan at Bailey Tire in Buffalo:
http://www.buffalonytires.com/
His price was $350-$400 cheaper than anywhere in Toronto. He also includes Hunter Road Force Balancing as well for a very low price.
They both make ordering from Tire Rack look expensive!
If you go to either shop, let them know I sent you!
- Kalson