Dude,
I was in the same boat as you. You're not going to find a lot of women who will allow that but if you are going to find any, it will be at Octopussy. I've got luck three time with three different women allowing me to finish in their face. And at the end I sincerely thanked them for being such a sport. And I cleaned them up...it was the least I could do.
In terms of price, they treated it like an extra option, ($20.00) and I advise that you ask to do it towards the end of your session. A lot will depend on the chemistry you have during your session as well as your appearance. If you look like a crack head from off the street then there will be no chance, but if you look like a clean cut guy healthy guy, then you just might get lucky.
Do a eforum.xxx search on facials. Some stuff should come up.
Good luck with that, and if you find any, let a bro know.