This is a pretty interesting idea and I like the idea of the site itself. What percentage of tutors get work at the rates they have posted and how many hours do they get on average? I'm curious to know if anyone is doing anything besides getting beer money (so to speak) with the site right now.
100% of tutors are booking lessons at their posted rates, actually - no real haggling going on. I think it's a different situation relative to, say, freelancing. You're not negotiating with a business over a deliverable, you're part of a transparent framework where people are trying to get educated. It's a different kind of motivation.