What's hanging me up is that if it's a print or reproduction of some kind, you'd think that there would be more out there.  And that it would be popular enough to warrant reproductions.

I mean, if it was a convention artist, why did he choose such an obscure character to make duplicates?  If it's from a famous artist, how come no one has ever seen it?

Something isn't adding up.  To me, it seems like it's an attempt at pop art by someone who is an unknown with a common name.  My online Sherlocking is ultimately not good enough for the task at hand though.

I do not see any Frank Miller in this piece at all.