If I weren't looking for something younger, I'd be interested. He is scopey and clearly has potential to go higher than 3 ft since he is over-jumping that oxer by at least a foot. Being a little nervous in new places is no big deal, so long as he settles soon after. Working on him with the trailer isn't that difficult, so long as he eventually goes in- or just use one without a ramp. Having a buck after jumping is something that can be worked out by an experienced rider - so long as he isn't doing it because he is hurting. Adequan is expensive, but another maintenacne product might work and anyway, I'd probably put anything over 10 that was jumping 3'6 or above on some level orf premium joint supplement. The hock injections aren't great, but depending on how often he needs them, might not be too bad. Ultimately, for an good rider looking to get a horse that is jumping at 3ft with the potential to go higher for free, and who can afford the maintenance, he looks like he has the potential to be a great deal. And at least the seller is being honest - that counts for a lot in the horse industry!