I strongly recommend against selling celebrity lookalikes. The relationship between fan art and the producers is a tenuous one and the quiet understanding is that you have tacit permission -- until you try to profit from it. Celebrities own their likenesses and the courts are unequivocal about this. Even Einstein, John Wayne and other dead celebs have estates which license use of their likenesses. Copyright/trademark violations are the kind of thing that sites which have explicit TOSes don't generally approve of (because they'll be threatened with takedowns).