This beautiful piece of original Robert Crumb artwork is on eBay right with a Buy It Now price of $14,500. I loved it before I even noticed that one of the robot's noises is "Boing!" From the item description:
This is original art for an unused cover for an unspecified issue of Inkling. The art is undated, but was probably done in the late '60s, as Mr. Natural, who appears in the piece, wasn't created until 1967. The artwork measures 8" x 10.5" and has been tastefully matted and framed to an overall size of 11.5" x 14".