I'm glad you made this decision to be honest. From what you have posted in the past, he seems like a horse that an experienced trainer needs to deal with. If he hasn't gotten better since you purchased him, I wouldn't raise his price, but some people get lucky with that stuff.
You said you have a couple other horses right? I, personally, would put the money toward a round pen to work on equitation (balance, etc) with my other horses. this is me, of course, and you definately don't have to listen to me
But I do tell you what, you ride a horse in a round pen bridleless.... it will give you quite a work out!! It also fine tunes your communication skills with your horse.
Good luck!