When I need just a sheet or two I go there too. Hobby People also has a pretty good selection. They both sell Mid West wood and it tends to be hard and heavy not to mention the cost but sometimes I'm looking for very hard balsa and it's perfect.
By buying my wood in bulk I'm able to get it in different grades, usually contest grade. I always buy way more then needed for the build I'm working on and after time I have a lot of wood on hand. Once I had nothing going on in my shop, not even repairs. Pulled out some plans and built a plane with the wood I had and called it a free plane.