She looks like a good enough mare for low level gaming. Have you tried her out yet? She's pretty young but it sounds like she has a good mind.
If she were on the market in California I would expect to pay around $1,000 or a little less for a grade. I paid $1,250 for my well-bred, greenie QH. Looks like she has no breeding to really go off of but if she's trained well and has a good mind she could be worth around the same.
One thing that concerns me is her age for her training... If she was greener than they say she is there might not be a problem but it leads me to wonder how early they started her for gaming. May lead to joint problems early on in life if they started riding her pretty hard at around 2, and it can take awhile to train a gaming horse. Again, I'm not sure how well she's trained under saddle but the fact that they're showing her already makes me wonder.
If anyone thinks differently, they probably know better than I do, though. Take my opinion on this with a grain of salt! ;)