Thanks for all the input, guys. I think I will go and look at the horse. I can do a pretty good job of remaining objective in most cases so I think I should be able to resist buying him just to "rescue" him. If the horse is looking very bad off, I do know of a very good rescue in the area that I can try to get involved.
At this point I'm willing to take a chance on a horse that isn't too expensive, knowing that I could then afford extra training if that's all the horse needs. I'm currently returning a horse that I brought home on trial who was NOT an inexpensive horse, and once separated from her owners turned out to be quite dangerous and in desperate need of full-time training, but at the price they were selling her for I couldn't afford to send her off to a trainer immediately.