Hi! She looks like a beautiful little dog. As for the re-homing fee, I have come across many Yorkies that are far older at rescue sites that are that much as an adoption fee. I think when people get a dog and have invested money, they try to recoup as much of their investment as possible. It's sad, but that is the way the world works. I would take someone along when you go to see her. I am nervous about ads as well. Hopefully, the ad turns out to be exactly what it says it is and that wee girl will get a home where no one will ever want to give her up.
Best of luck.