Curious how others mark up some of the larger sized plexi available. We do a decent amount of the 60"x70" range of framing and usually get that plexi cut to size. The regular stuff is not that expensive but we are about to do two orders for the Optium Museum plexi and that beautiful stuff is the price of a used car. Anyone willing to share what type of mark up they do with it?? I can't see even doubling it!