A car that runs and passes inspection/registration (depending on where you live) is worth $500. Your best bet is probably a newer econobox with their horrid depreciation (Ford Festiva or Escort, and just about any Kia, Hyundai, or Geo).
If you know anything about cars, or are willing to learn, an older domestic can be a good deal. The monster sedans of the 70s and 80s are just about bulletproof and there are thousands of them sitting in garages of the elderly all across the US. It's pretty easy to find a low-mileage car that really has just been used just to go back and forth to church on Sunday. Take a look under the hood, you'll probably want to replace any dry-rot belts and hoses, but other than that most are in great shape.
The older the car, the simpler the mechanicals under the hood. While 4x4s are going to be out of your price range, you could also get a 2 wheel drive pickup pretty cheaply. Rust will probably be the most common problem you find, but as long as the drivetrain is in good shape you can drive it until the body falls off around you. Pick up your local classifieds or autotrader-type rag and really look over every auto section.
