Good ol' Rona. It's like being lost in a giant warehouse for days on end, except at the end of it all, you get to buy the parts to build something.
This particular Rona isn't nearly as extensive as the other ones I've been to, but if you're looking for something pretty common there's a good chance that they'll have it. Since it's located in the middle of the city it's a good stop for your every day household fixer upper needs without needing to make a trek out to the distant burbs.
Rona favours selection and price over service. Chances are it will be tough to track someone down to help you out, let alone someone interested in helping you more than just calling out an aisle number and disappearing before you can get back to tell them it's not there. But on the other hand, they have free popcorn, so...