The store is great, particularly some of the descriptions. If I had the gold I would be interested in a few things, the snail t-shirts are awesome. As for additional items, perhaps posters/prints, I know there is a lot fans of the amazing artwork here. I'm not sure if a book is feasible or financially viable but there may be fans willing to invest in a bestiary or making of etc.
I want a slime in an alcove. Or maybe just a dungeon alcove on a shirt.
'Cause I'm the alcove guy.
Also, that enter symbol shirt design looks really freakin' cool.