Look at the following eBay auction for an HP 29C:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=5773145209
The main image is obviously wrong (showing a 19C from a different auction) but there are additional images & text, telling that the device in question is actually a 29C.
The price, $510 at 2 1/2 hours before end of auction, is ridiculous!