If she's traveling just to see you, I'd be more inclined to make the deposit.
Travel expenses. Gas, Food, Hotel, ect. Why should she take a chance on losing money if you back out?
Yep, she could back out and you could post a warning on her local board. Not with her name but just an advisory with a comment to contact you privately for details. Once the word spreads.. well, you get the idea. She really has more to lose than you.
Ultimately, only you can decide if its worth it.
Do NOT rely on the appearance and performance marks for this. Read the reviews and look for statements indicating flakiness or inconsistencies in her reliability.