This sounds like a horse with potential but a bit of a tough sell at the present moment. Your best bet might be to see if there is a sales barn with a GOOD REPUTATION that sells horses of his type (green local show horse material horses) and see if they will take him on consignment. If it is a GOOD place (and make sure it is) they will ride him and keep him in a program and even if he doesn’t sell, he will not come back in a worse position than he is in now. Honestly your own ability to market and sell him is probably fairly limited and he doesn’t sound like an easy-to-sell horse. I would not expect to get over $10K and only that if he is truly a great mover/jumper and if you happen to find someone looking for exactly what he is (green kind of tough horse).
On a gelding of this sort I don’t think papers matter tremendously. What does matter is his size (smaller than what a lot of people prefer [FBOFW], green for his age [at 8 most horses are jumping the height they’re going to ultimately show in with changes and have a nice show record], tough [many people are going to find that taking off at the canter business to be a dealbreaker and it sounds like his groundmanners could regress quickly too, also he has the history of rearing and bucking you have to disclose]). You have a kind of tough, kind of old-for-his-experience green horse of an average size. Unless he is a stellar talent under that greenness, this may be a harder horse to sell.