@Germlat,
This conversation started as a discussion of why men need prostitutes.
I pointed out that as far as casual sex goes there are a very few desirable males that most available women sleep with. The rest of men, who aren't lucky enough to be judged desirable by women, find it very difficult to find someone to have sex with without offering something (i.e. money or commitment or both).
This started with the observation that (for men at least) free sex is the most expensive kind of sex.
I think I have made this point well.