Cheap places to buy groceries

Wal-Mart opened up a few of their Super Centers in the Greater Toronto Area a few months ago, and while I hate the fact that they're such a ubiquitous thing in the retail landscape nowadays, I find myself shopping there frequently. Especially right now because I'm trying to save money, I find it's the best place to go. It has surprisingly good quality fruit & veggies, and good prices on a lot of the other items I use every day.

I also like to shop at the Real Canadian Superstore as well, as it also has good prices on the things I use & buy every day. Surpringly, the Superstore in Oakville has better prices than the one in Don Mills (in general), which I find interesting. How is it that the different store managers are able to charge different prices for the same items? Is it a franchisee versus corporate store issue? Who knows, all that matters is that I can find cheaper prices on bagels and juices than elsewhere.

Where do you go shopping for cheap groceries these days?