Hi, I'm no expert but I do browse the horse for sale ads for recreation, lol. (I didn't stay in a Holiday Inn Express last night, either lol). If you are an experienced rider, I think you'll want to find an OTTB. You can find a really athletic horse for cheap. But you have to be able to train it yourself. Try CANTER
Here in Virginia you would not have a prayer of finding an athletic jumper that was already trained for 3,000, unless you do the OTTB route.
I ride at a hunter barn with frequent sales horses going through (some in the 25,000 price range). In terms of natural jumping ability, I think you''re looking for Irish Sport Horse, European warmblood, or thoroughbred.
I would also recommend a couple issues of practical horseman. They have a conformation clinic page that goes into a lot of detail on pastern, shoulder, etc, and it's almost always focused on jumping.