just print up a few different pictures where he likes different aspects and tell the artist to draw it up so he's not going to have the same tattoo as someone else out there.

I took 3 different pictures...each with different things that i like about them and had the artist draw up some bad ass sh!t when i got my second one done. Said it was an original idea and that he really enjoyed doing it

EDIT: plus most tattoo art sites charge. Just find pictures of artwork. Mine was composed of posters and a statue