I build my own kitchen cabinets, I did so at my last place and I am doing it again at my new address. I have shopped around the Ottawa area for quality lumber and I can tell you that for price, quality and selection, nobody beats The WoodSource.
I decided to use birch because of it's hardness, grain, and price. I purchased 1x4x8 birch boards at The WoodSource, to start my cabinet doors and the wood is pretty much flawless, without having to dig through the whole stack to find a few good pieces, like you have to do at some other stores. Not only that, but I was not able to find Birch at another store.
If you're looking for quality lumber for a good price, look no further, and whatever species you want will be here.