Are you serious? I'm fairly sure you're protected by the first amendment for selling MLK-Hitler posters. In fact, you can Google for those items now. Here's one:
http://www.redbubble.com/people/artofmewa/works/8484381-the-...
9 karma · joined July 29, 2013
http://www.redbubble.com/people/artofmewa/works/8484381-the-...