He is worth what you feel you can replace him for, to insure. He is worth what someone is willing to pay, to sell. Maybe get an appraisal?
Personal experience however -
I am pretty surprised with the prices some of you are throwing out! (Meaning no disrespect to how nice he is)
One of my students re-purchased a horse that I'd rescued and trained in 2010 - she bought him back from someone this past spring. She had never ridden a barrel horse nor had any lessons barrel racing. Practiced for two weeks before her first show and this was their first run together.
They, she mostly, made some mistakes but ran low 17's for the first few shows and by the last three shows were in the high 16's, never hit a barrel. Plus this gelding is actually a far better pole horse than he is a barrel horse so she is really looking forward to their 2014 season, now that shes getting the hang of it.
This horse is also not hot at the gate, rides in a training snaffle bit (no chin strap, no tie down), is schooling dressage, trail rides, loads, bathes, clips, ties, easy to catch, etc... I had gotten him for free before we did any training with him. Did not sell him for much because I've always found selling a barrel horse to be hard and she just re-purchased him for $1,000. Your gelding being younger, registered and pretty I would have put him around $5,000.