I've thought about it enough to know that I don't have a single price. The price depends on attraction, how much I like and trust a person, assurances of discretion and safety, etc. My "ideal" price is zero; I sleep with people for free all the time. Above that, it gets complicated. For example, I can think of a certain girl who's extremely unattractive, abrasive, not very bright, always hard up, and likes me a lot. I definitely wouldn't do her for free; I've been tested on that extensively. $500 would be enough. However, she's in debt, she's a friend of some friends, and she can't keep her mouth shut. Everybody would despise me for taking that much money from this girl who's struggling personally and financially. There's no good price for that example, but it's the most likely example I could come up with in real life. If I imagined she was better-off, $500 would be plenty for ninety minutes of work (including drive time, chit-chat, etc.)

This is an interesting, and IMO uncommon, response. Thanks for the honesty! :)

You're right social constraints are going to modify each condition; many people sleep with others in sympathy, for example.

If I imagined she was better-off, $500 would be plenty for ninety minutes of work (including drive time, chit-chat, etc.)

That's an interesting figure; because it is roughly how much a prostitute would be paid (I use that example only because it is the most readily available price for sex we have). So, possibly, there is an inherent social value for non-free sex we subscribe too.

My "ideal" price is zero; I sleep with people for free all the time

This syncs almost exactly with the response most men gave in our survey