Here is a link to a heart-warming story about a lady and her hen. http://www.chron.com/news/article/Massachusetts-woman-s-chicken-getting-prosthetic-6421080.php Personally, I think I'd just get a tiny crutch.
WOW that a heck of a lot of money to get the leg fixed!! I hope the operation is a success though and that the hen recovers well and is able to live a normal life.
Eileen, I wouldn't even try to define "normal" for a chicken. They seem to go from strange to stranger, but I'm sure this hen will adapt well to her new leg.