No idea if it's allowed to discuss other sites here. If so, I apologize, just delete.
The topic of escrows came up, so I'm not too sure of how many people know about extralunchmoney.com but I've used it for years.
You can post a project, girls who are interested click on it, you can then view their profile, read their reviews, see their ratings and hire them for the job. You can also do a search and contact the girls directly.
You pay upfront but it's held in escrow. You don't release the funds until the project is delivered and approved. It's very tough to get burned.
Do be aware that the models only take home 60% of what you fund in escrow.