So are you thinking about buying her? First, I would tell the seller just how poor this little girl's health is, and if anyone offers to buy her they would probably not pay much if anything because of her condition. If you think you are prepared to take her on, you will need a herp-savvy vet and the $$ for treatment just to get her stabilized. You won't be able to correct her current limb deformation very much, but you can probably keep the MBD from progressing. She's very dehydrated in addition to the MBD. You won't know what sorts of internal organ damage may also be going on, so be warned. In addition to getting vet support and calcium treatment, give her correct UV lighting (you didn't say what sort of bulb she has now), well gutloaded feeders, and the correct calcium and multivitamin dusting schedule, and a lot of hydration.
What a shame anyone would treat a cham so badly and still try to SELL her!