I'd try the Ethiopian spice shop in Kensington Market.
Most Ethiopians in Toronto don't actually make their own bread at home, though. Almost all of them buy it (and in certain areas, like Parkdale, you can get it at every corner store). I had a conversation with a man buying it one day at my local Hasty Market, and he explained that western-style stoves aren't suited to the mitad pans used to make the bread, and that because of the climate here, it's harder to get the proper level of fermentation. I had mentioned that I was interested in making some myself and he shook his head, and told me I should just buy it instead.