You would probably find far better luck getting interest from an artist on Hentai Foundry. It is the Deviant Art of adult art. Most of, if not all of, the artists you see in these games are active on there. You will find both 2nd and 3rd artists, animators, and flash animators on there. Unless you are very lucky, you will have to pay. Commission fees vary artist to artist so who ever you talk to, you will have to ask them what compensation they feel their time is worth.