I would like to know where to find sketches of Beelzebub's anime. I've found on YA some of these sheets in which are drawn the various character's expressions and styles, but for what I understood, they are only copies made for the employees (it must have a name, but I don't know it).
The anime in itself is pretty recent (it has begun one year ago), so I'm not sure that the sketches are already being sold by the studio.
Keep an eye on Mandarake. I've seen the series name show up there, but only for settei (the copies of characters you describe) and, IIRC, a copy storyboard. But for recent series rough sketches sometimes show up there before anywhere else.