I just have to walk a few hundred yards and I can harvest mesquite, it seems to be my main wood
every year I go up to the mountains where the apple orchards are and get the trimmings from the orchard before the commercial companies get to them and jack the price up 5 fold. I love the taste of it with chicken and fish and such
I use oak I can source for Texas style brisket and such, I have a friend that receives heavy material on oak pallets, I get one whenever I need oak and cut it up. So I get about 50 pounds for free
I also do some wood work and use the scrape from that. Maple, Ash, etc, but that does not build up much.
I would use Hickory but I find I have to buy that and all this other stuff I get either free or dirt cheap. If you are at all resourceful and have a truck you can find a lot of wood free, I keep my house heated with hardwood I pick up free, I have made friends with a few tree trimmers and they call me if they have a job on the weekend. They have to pay to dispose of it. I just found 4 pickup loads of Oak from a tree cut down, I saw it in the FREE category on Craigs List.
It is amazing the wood getting thrown away out there, and the difference between hundreds of pounds for free free and the equal amount of bags bought a the box stores is almost criminal.