Well, first of all, I think she's lovely. I think she's a terrific sport pony type, and I love her and want her. Her confo looks more suited to dressage to me; she definitely has the uphill build and neck shoulder connection of a dressage horse.
Pricing her is problematic - she's not really a kid's pony; so your market is a petite adult. Then you have to look at your area and see if someone's serious about competing; would they be willing to compete a pony and a pinto at that? I would look at warmbloods of similiar age, price, movement and training in your are and then discount the price slightly. I don't like it, but she will not have the same market or bring the same price as a WB with similiar attributes.
I think her best market may be as an event pony. She has the movement and solid foundation to rock the dressage, and there's absolutely no prejudice against color or size in that discipline. Adults can compete ponies *very* successfully. You could probably find a solid C or B pony clubber (Or a petite skilled adult) who could get her going over fences and she'd be awesome. Right now, however, you'd be selling her as a green prospect. A spectacular one, but still a green prospect.
Third potential market for her is as a hunter pony. She has the movement to win the hack, no question, but your photos don't show her form over fences, and she's some ways away from being finished enough to jump a hunter course. So again, you're selling a very talented green prospect.
Bottom line? Getting her started over fences is the best way to increase her value.
Or just send her to me.