Here is one for the Canadians (especially ones from Ontario looking to re-locate to a more pit-friendly province)
Animalerie Little Bear - corner of Greene and Sherbrook west in Montreal.
This is truely an awsome store, they have everything from premium kibbles, BARF patties, supplements, toys, treats.....and they are always getting new stuff. They are really great about giving you good prices on large quantities of food and will deliver for free if you can't make it there.
The owner also has the sweetest, and hugest, black pit cross in the store with him.