Colin, do you a fireplace shop around you? There is a fireplace shop by me that just sells different types of wood to burn, not even necessarily for cooking.
I couldn't believe it when I walked in, but they have Pecan, Maple, Apple, Black Walnut, Hickory, Oak, Peach and a couple others I don't remember now. A 25lb. bag is $20 or so. The only problem is they tend to have a lot of bark on them.
On another note, has anyone ever tried using Birch to smoke with? I've got a bunch of dead birch trees so I figured I'd give it a shot. Also, does anyone think it would be a problem to cut the wood up using a chain saw? I just wonder if the chain oil would be a problem.