I'm trying to see this idea, but I can't quite turn the corner on it. Initially, it might work OK. Provider A needs X amount of money for whatever season and Hobbyist B is offering Y. They agree to hook up and everything's dandy. At some point this concept would lose some steam because guys would eventually 'test the waters' and see just how low they could get a provider to agree to their 'allowance'. Providers see 10 'man ads' and 8 of them are insulting. Then you may have one provider who may decide that seeing a few guys at their low allowance could be to her benefit. Provider B sees a little less business in HER direction. A little mud may be slung and things could potentially get out of hand. Quality and satisfaction of services may dip as well. Provider could say, "You only gave me THIS amount. What did you expect to get for that?"
It's negotiating is what it really is, which is something many ladies say is not an option with their set rates.
Wouldn't it be easier to just put together enough to get 1 good or great session over a couple half assed ones?