I've ditched that horse, or at least put it way in the back of my mind. After talking with some people in private messages, I decided that horse I posted a picture of was probably misused and will have lameness issues soon if not already.
I'm getting really close to going and looking at another AQHA mare, 15.3hh, 2001. She has pretty nice conformation other than a high withers, which I think is preferable to most other faults, considering I'm very unlikely to find a young horse with "perfect" conformation for $3500. In any case, if the (slightly) high withers is the biggest issue, the horse is probably a home run.