Answer would depend on the source of the artwork files and if it is Classic Arcade Grafix dump that a number of vendors picked up on back in the day. If you get access to that (and probably more), $30 doesn't sound like a bad price. Back when a number of us paid $50 just for the CAG files.
Of course, there are vendors who also provide printed artwork from that same CAG stash, so if you are looking for a particular piece of printed art, you may be better off elsewhere.