Prince's iconic demo tape up for auction.

The demo tape that launched Prince's career is up for auction, containing unreleased versions of three original songs recorded by Prince in 1976. The tape is part of the Marvels of Modern Music auction and comes with a plexiglass display case, a business card belonging to the music executive who signed Prince, a CD transfer of the tape's audio, and a letter of provenance from the person who discovered it. Other Prince items are also being auctioned, including a lace glove he wore on stage during the Purple Rain tour and a sealed first pressing of "The Black Album."