While old cars are neat and fun, if you rely on it for school or work, get something newer, with lower miles, that is reliable. Make sure to test drive it and try EVERYTHING on it. Floor the gas pedal, floor the brake pedal (while cruising at 20mph or so), steer all the way both ways, check reverse, engine startup shutdown multiple times, radio, AC, heat, windows, locks. Make sure the tires have tread left and are not cracking. If you can fit, get underneath it and take a look at everything down there, especially any rubber parts. Check the belts and hoses under the hood for cracks. The engine compartment should be dry and dusty, not all wet and oily anywhere. Use ANYTHING that is wrong as a bargaining point.If the owner doesn't know when the oil was last changed, better move on...
As for what kind of cars, you can always make a lot of friends by owning a pickup truck (I would recommend the Ford Ranger)
. Seems everyone always has something they need moved. (especially robotics teams). For a reliable car, you should be able to pick up a late 90's or even early 2000's Honda Accord or Civic for your price range. Those do tend to be targeted more among thieves though. Bottom line is, get whatever looks good and feels comfortable to you and fits your price range. Just be sure to do your shopping homework and not pay too much for what you're getting.
Good luck! Cars are fun!
EDIT: Forgot to add, check all the fluids that you can see without any disassemble. They should be at their proper levels, smell and look normal, free of any metal particles, and not cross contaminated. And when you drive it, roll the windows down and listen carefully to see if the car makes any strange noises. Also, if it is a private party, ask them their reason for selling it. If they don't have one, the reason may be that something is broken on it or about to be broken.