Buying a good, cheap, used car has been really, really, really difficult for years.
The last three I've had were through acquaintances (friends, friends of friends, family, coworkers, etc). If you can, look for a car this way. Maybe someone is getting a new car soon and is going to trade their old in for not very much money... maybe they have a parent who is giving up driving... or someone passed away... Sad but those things happen and those are usually well maintained, low mileage vehicles as long as dings and dents are OK.