Broodmares are really hard to sell these days. It's a buyers market and folks who are still breeding will rightfully only pick the best of the best. Excellent pedigree AND conformation. Without knowing her pedigree to judge a base price without the pigeon toes, I would guess maybe 200.00 to someone who can put some training into her for a light riding family horse.
Other than your vet, have you had any type of barefoot hoof specialist look at her? Have x-rays been done? We've taken in some rescues that were written off as hopeless by regular equine vets but straightened out over time with proper barefoot hoof care. Has she ever worn shoes? If the vet you saw is a specialist, then I'd probably take his/her word for it, though.
Good luck with your mare. She has a sweet face.