The problem with Toronto is that there isn't really a retro video game scene. There are a few stores that have a few old games but they are usually over priced. A & C games is by far the best place in the city to buy retro games, they carry a huge collection of games from many consoles. The store is a little small but it isn't a big deal if you go when they open which I tend to do. The prices tend to be a bit high compared to other avenues but it isn't that big of a deal to effect its rating.
Overall A & C is the best place in the city to buy retro games from, you should check them out if you have a chance.