Where is the rim bent, at the edge or does the whole thing wobble? If the whole wheel wobbles, the mounting plate in the center is what bent, and there's not much of a chance of straightening it.
If it's just on the edge you should be able to just beat the hell out of it with a hammer (no heat) until it's back in shape. I never tried it myself, but witnessed my jackass buddy rail a curb in reverse with his cavalier, putting a v-shaped bend into the wheel a couple inches deep losing all the air, the dent was so bad the rim was hitting the rear control arm and locking up. His spare tire was flat, so he proceed to beat the hell out of this rim with a claw hammer. I'll be damned if he didn't get that thing straight enough that not only did it hold air perfectly, it didn't even mess up the balance. And i'm not talking about a master craftsman either, i'm talking about a jackass that tries to do a reverse 180 in a mall parking lot with a 92 Cavalier and failed horribly, slamming into a curb at 30 miles an hour. It was a steel wheel so it was probably a little more workable than an aluminum one though.