James,
If you are looking for something close to a traditional packer your best bet is The Butcher Shoppe. The downside there is that they cater mostly to restaurants and hotels. They don't really have advertised prices and you are at the mercy of the guy running the retail corner of their butcher operation on what you will pay. That said, the more you buy, the better the price tends to be.
The other place that I have had some recent success is European Meats in Kensington Park in downtown Toronto. I used their briskets in recent BBQ comps. One of the briskets got me a 2nd place call. However, their briskets tend to have relatively thin flats and are usually trimmed up a bit more than I would like.
Highland Farms has briskets from time to time, but they tend to just be the flats and are pretty well trimmed. I haven't actually bought one from them, but I do like their meat counter. They often have good prices on pork spare ribs.
I hope that helps.
Cheers,
Scott