Looking at horses to buy, and he is a potential looker (:
Whenever you take a picture from an ad you should link the ad as well.
This was the very reason I did not comment. Also realize that when you are looking at sites that are not for sale sites..the taking of one picture is not the kosher thing to do. ( some can be under copyright)
The pictures of him 'working' alot better confirmation wise, maybe he was just being lazy in that first picture and let his neck slouch?
I think he's a little underweight and undermuscled as someone else said earlier as well.
I'm all for doing a trial lease before putting that much money and hope into a horse. That gives you enough time to learn if you get along, as well as what he's fully capable of if you work with him as often as possible so that you know if he's easy to collect and so on.