I'm assuming you don't want to buy tokens either. I checked out the site, and one chat had 2,500 viewers logged in.
I think you're SOL on this one. My opinion on these type of sites is that models are going to do what they do, no matter what. A percentage of people will get what they want, simply because she was planning on doing it anyway. That makes a percentage of people feel like they won. If you're asking her to do something really odd or fetishy, your chances will decrease. Especially with no cash going her way. Get too aggressive and the mod will kick you off the page.
Remove factors from the previous paragraph. "1 in 2,500" is one of the odds in the Pick 4 lottery. It's also the chance a baby born in the UK will have Cystic Fibrosis.