Around here, a horse like that, proven 1D-2D who is sane and sound, can be roped off of, and is suitable for an advanced child rider would easily be worth $8K to $10K, probably more.
Just browsing my local sale ads: Keep in mind that these are just the listed prices and the horse may or may not sell for that price
6 year old gelding, similar temperament, 3D times = $8000
13 year old appendix gelding, slightly hotter temperament, 1D-2D times locally, 3D-4D times against really tough horses = $10000
Gelding, unknown age, breakaway/heading/heeling/barrel/pole horse, 3D and 4D barrel times, kid/beginner safe = $8500