I know lots about Tonner. I also have this doll.
If your Princess has a braid, she is the second Tonner Rapunzel doll, and is currently available. I think MSRP was just under $200. If your Rapunzel doll has long, straight, unbraided hair, she's the first edition and a bit harder to find. Generally she's available on eBay for about the MSRP, maybe even a bit less. Tonner is one of those weird companies where it generally depends on the fandom to determine value increase/decrease. Many of the Disney Princess Tonner dolls were kind of flops and ended up being clearanced out if I'm not mistaken. (Some of them had really funny looking faces, others, like Tiana, were really beautiful IMHO.)
Tonner has had a longstanding relationship with Disney, starting with, if I'm not mistaken, a line of "its a small world" Dolls.
Frankly, I love my Rapunzel Tonner. I think she's gorgeous and I wouldn't trade/sell her for the world. I think the detail work on this doll is some of their best, and the likeness is much more accurate than many of the others they've done.
EDIT: Here's the link:
http://www.tonnerdoll.com/disney-princesses/tangled