First, I would not pay a single dime for it. Why reward them for not caring for the snake in their care?

IF you get it( and I would hope you'd only take it if you can convince them to give it to you for free), you should quarentine it FAR away from any other reptiles or birds you may have. NO cross contaimination. Seperate everything, and forget hand sanitizer, use a decontaiminating solution from a vet.

You'll probably have to take it direct to a vet to check for parasites and infection. While it's on antibiotics(if it's necasry) it will not eat. Clean paper substrate, good humidity, fresh water changed daily. Maybe a humid hide, and lots and lots of hiding spots, maybe some crumpled paper balls to help it feel secure.
Good luck, but please don't pay money to them for the snake.