Adopting a cat and paying for previous vet bills; Right or wrong?

Someone is "giving" away a cat that I really like on craigslist. They say it's half Himalayan and half Persian. They said that she has a cut on her neck because she was caught in a fan. The vet bill to take car of the kitten was $125. She wants the adopter to pay her back for the vet bill.. but I personally feel like it's not the adopters obligation to pay for it because it wouldn't have happened if not for the current owners actions. (Not watching the cat, etc.) However.. I really want this kitty. Not because of the mixed species, just because of the way she looks. Should I pay the bill or maybe offer a negotiation? If so, how much should I negotiate? Any other advice is welcomed.