There's a Restaurant Depot in Buffalo. They won't have King Arthur flour, but they will have bromated flour- which is superior for NY style and unavailable in Canada.
500 Duke Rd
Buffalo, NY 14225
Someone may chime in with a source for Ezzo, but, should you cross the border, you should definitely try swinging by a supermarket and getting Hormel Rosa Grande (thin diameter) or the Hormel Leoni (wide diameter). I prefer it sliced thin, but it doesn't keep all that well sliced, so, depending on how long your trip is, you might want to buy it whole and slice it yourself or find some way of freezing it/keeping it frozen. Sliced pepperoni lasts about a week for me in the fridge.