An old coworkers wife was a detective and she got called into her bosses office one day, boss asked her if she'd be the prostitute in a prostitute sting. They took a bunch of body shots (no face) and posted them on craigslist and had some set price for her that was the going rate for her age, weight, looks, etc... Like they seriously sized her up and put a price on her, and one of her hotter coworkers of course was worth a lot more.
Keep in mind she was in her late 30's and had a kid already but was still decent looking.
They set up appointments at some hotel where they had interconnecting rooms, and had her room all wired up and she had specific instructions on what she could say and couldn't say, could do, etc... and cops in the adjoining rooms where watching them on camera and listening the entire time. They set up like an appointment every like 15 minutes and just ran through like 20 guys in a day. She had to bang them all so they could charge them.
Ok, so maybe she wasn't allowed to touch, but she wasn't allowed to bring up payment or anything. She just had to talk to them and dance around the subject and soon as the guy offered money or payment for sex or something sexual the cops in the other rooms would storm in and arrest him. One guy just wanted to watch her get naked while he beat off, but didn't want to actually touch her because he felt guilty about cheating and somehow that was OK? One dude had recently lost his wife and was just lonely. Some were just creepy and desperate.
So yea, never bring up price, let the prostitute ask for payment after you bang her.