I purchased wood at Home Depot but they are limited to Hickory and Mesquite. Are there places on the web to purchase various wood types in small amounts?
Wal-Mart has wood in the grilling and BBQ section. It's usually very cheap. Most specialty BBQ outlets like BBQ Galore also sell a wide variety of wood in chunks or chips sizes.
You should try visiting a local fruit orchard. They would have trimmings from broken limbs and pruning. They might let you have the wood for nothing, or in exchange for a couple racks of ribs.
I've been trying to give away apple wood (have a small orchard). If you are around mid Illinois I can get you a years supply of apple in a few minutes. Otherwise I end up burning it.