From an Ebay auction, via
a post on the 2 Warps to Neptune blog.
The front of the shirt shows the dragon from the cover of Dragon #1, along with the "Come Visit My Dungeon!" slogan, also seen on
this sticker from the time period. The back has Greg Bell's Lizardman art from the inside cover of Greyhawk, also used as the "Lizard Logo".
The
April 1978 Dungeon Hobby Shop Order Blank lists a "D & D Shirt M, L, XL" for $4.95, possibly this shirt.
On G+, Ernie Gygax commented "Yes this was a very common item at the original 723 Williams St Dungeon Hobby Shop. I really do not remember the price but I may speculate that $8 was very near the mark."
Zenopus Archives
website &
blog: Exploring the Underworld of Holmes Basic D&D.
Holmes Ref: Reference Sheets for Holmes Basic Referees, also compatible with OD&D plus the Greyhawk supplement