I made my own out of some round bar and pipe I had laying around. On the grill itself I heated and bent both sides down around the pipe so they're on permanently. On a smaller grill I built a few years ago I just bent one side so the door could be slid one way and removed. For the firebox I only bent one side but did them on opposite sides so its not removable either. A trick to making the doors fit right is to weld the hinges on right before you make the final cut on the door.
I get expanded metal at a local welding shop, for a little extra they even cut it to size for me. That's the only place I know where you can buy metal in my town. Maybe in a bigger town they have welding supply or metal supply stores that would have the stuff. Sorry I couldn't be more help.
I've yet to build a charcoal smoker, but I've been around a few wall tent stove builds. Wood stove places are the best source of parts I've come across for parts for BBQ and smoker parts. Hinges, handles and the like. Here are a couple of sources: www.stovepartsplus.com/ www.woodmanspartsplus.com/