She is very cute, and I am a sucker for red TBs! I owned a small red TB mare in the past and she was flighty, sensitive, and she hated to stand still. I used her for trails and pretend polo. She was a one-of-a-kind horse that it took a special person to understand, which made her invaluable to me. I understood her quirks and what she "liked" and "didn't like". She was my baby, but to everyone else who didn't know her like I did, she was just another hyper red TB.
I think you should keep that in mind as far as her 'worth' goes. YOU know this horse, YOU understand her. So when people say "Meh, $100 would be all she brings in" YOU know that she is worth so much more emotionally. There's no way on earth you'd let her go for $100, even if that's all she's "worth" ;) There are tons of red TBs, but there's only ONE Sunny!
Keep her, break her, enjoy her, and then if you have to sell her later on, give everyone a reason that she's different from all the other red TBs. :) She's extremely cute. And she looks JUST like the mare I was talking about earlier. Best of luck!