For the yearlings I've sold, buyers have done xrays of front feet, knees, hocks, and stifles. I do not allow flexion tests to be done on my youngsters. The vet also thoroughly checks the horse over, including taking vitals, look at the eyes, conformation, palpates the legs, and watches them move in hand if they are well-behaved (at the walk and trot), and/or free (w/t/c). I have had buyers pull blood for a drug screen, though I definitely don't consider that the norm.
In my area, I would expect to spend around $1,000-$1,500 or so.
We try to do baselines on all the horses/ponies we put up for sale but it is costly. I had thought the digital xrays would bring the costs down - it seems to have made them more expensive.
We also don't allow flexions on horses/ponies until they are 3. I don't need some over zealous Vet injuring a youngster that I have for sale.
Summit Sporthorses Ltd. Inc.
"Breeding Competition Partners & Lifelong Friends"