BoingBoing friend Mara says,
“The band Guided by Voices put out an album in 1992 called Propeller, and each one had an original cover hand-created by the band and/or their friends. There were only 500 copies made, and one just sold for $6200. Here’s a link to an article about the sale: Link.”
And here’s a guy who’s trying to collect images of all 500 covers: Link