I have a cinelli catalog somewhere from about 2 years ago that has all kinds of Eric Clapton and Cinelli stuff. It came in this special "Bootleg" concept packaging.
Cinelli reprinted a letter from Eric, thanking them for the bikes. It sure sounded to me that Mr. Clapton has had many Cinelli bikes over the years, so I wouldn't dismiss the one on Ebay.
grant mclean
Toronto