Posted By:
Richard L.Jim,
If you click on his items for sale and type in cardboard sign, he currently has 15 different one's as a BIN between 50-100 each. All advertised as vintage. I don't think you'll get a neg, but if so, make sure he gets a dandy in return!
edited to add: In addition to his 63 total negs, he has another 24 that's been "mutually withdrawn".