I don't know what I think about it right now, so I'll see what belief I should form here and now.
Well, it seems really simple. If two teenage friends ( one male and female) love each other so much, trust each other and feel comfortable with each other, and are at least somewhat attracted to each other, should they be punished by law for engaging in sexual intercourse? Probably not. So why should the inclusion of money being transferred make it, therefore, more wrong than without the money?
Either you regulate all non-marrital sex or you don't. And since there is no justifiable means for regulating it in the first place, you shouldn't do it. Therefore prostitution should not be illegal, and thus legal.