The Authentic Experience
eBay seller "chowbay" has offered several signed copies of "Popism" and "The Philosophy of Andy Warhol...", most of which contain a soup can drawing. In my opinion, the signatures and drawings in the books are all very similar in appearance, but differ from other examples I've seen. The books also sell for substantially less than market value.
Here's the current offering:
http://www.ebay.com/itm/130580008160 ($375 starting bid/$555 BIN price for a signed "The Philosophy of Andy Warhol..." with drawing)
Here are a couple of previous sales from this seller:
http://www.ebay.com/itm/130566691798 ($149 for a signed "Popism" with drawing)
http://www.ebay.com/itm/130538159340 ($495 for a signed "Popism" with drawing)