I have a solution about 90% complete that ended up getting cut short due to funding and backing out of a partner (personal issues). I still am very close with the developers (they've built 2 video chat solutions for me from scratch) and they've very reasonable pricing.
You can see the solution with some temporary data/profiles at
www.julietlive.com. I don't know what you're after and how much it may vary from a solution like this, but this one is fairly thorough (from tipping, private chat windows, various billing gateways, spending limits / "levels", internal messaging + gifting, and more) and can be modified to suit your needs.
If you're interested drop me a line on skype tical525 and I'll provide you with a bit more information.