Owl Hardwood should have most of what you want, and they do millwork if you need the planks cut to your exact specifications. My guess is that, including any millwork charges, the custom-cut planks will be less expensive than anything sold specifically for cooking...
I would stick to their domestic hardwoods, though, because they can tell you which ones are untreated.
Dumb question: has anyone thought about going to a place that sells logs for fireplaces, getting some apple or cedar/juniper logs, and splitting them into planks? (most "cedar" sold in the US is juniper)
Mark