In spite of me telling Herb how little I liked his idea of a "facetime" chat first, I think it's the perfect solution to your situation. It's one sure fire way to make sure you aren't getting catfished and spares you the very uncomfortable job of slamming the door in her face if she shows up 20 years older and 40 lbs heavier.
One other thing you need to find out. "What exactly does your $500 get?" I wouldn't phrase it exactly like that, but there is nothing wrong with asking "how much time can I expect to spend with you on each date" (the "each date" part of this is important, you want her to believe this is going to be a regular thing if she makes you happy) If she tells you anything to make you believe that once you cum she goes, you might want to rethink her $500 ask as you are now into hooker rates.
Sometimes these things work out well, I had a POT SB tell me right out of the gate it would be $400 PLUS wine. (That part intrigued me) I asked her how long I could expect our date to last and she responded "until you get tired of me" We met at her place, not mine, we ended up drinking four bottles of wine, I get there at about 7 PM and didn't leave until about noon the next day, we ended up going four rounds during our date, it might have been five, but after four bottles of wine she passed out on me after going two rounds in the evening, she more than made up for it with two rounds in the morning though. Damn, I need to go see her again, she was fun. lol
Alternatively, you might ask her if she is willing to host. If she turns out to be an OTHFB, you can always just turn around and walk out the door, which is MUCH easier than throwing her out of your place which can get kind of messy.