Okane ga Nai and Level C are essentially the same story told differently. In both cases we have a rather thin plot involving a strong shounen-ai element that includes sex as rent, as odd as it may seem. While not overly graphic in terms of content both titles have no qualms in being pretty in-your-face. Okane ga Nai has more angst and occasionally violent while Level C is sheer fluff but they are remarkably similar.
What would you do to get rich? Both Okane ga Nai and Meisou-Ou contain a young man (Two in Meisou-Ou Border) doing various shady schemes for money. Not only are there slight bouts of comedy within a dark situation, there is nudity and a cast of nearly all men. They both are very morally grey shows; you will either enjoy it or hate it.