I stumbled upon this listing on Etsy! Filthy thieves! I am going to assume they're using my low resolution version of my map which menas that anyone buying their largest version would be very disappointed.
Cyan is pretty restrictive about making money off their IP, and I've contacted them with regards to being able to sell physical versions of my Myst Book, but they haven't responded yet. Also, I reported the listing on Etsy. :/