Here's a link to a recent auction for a first-year (1981) HP-12C in mint condition -- first time I've seen one go for > US$500.
The seller certainly knew which significant points to emphasize...
A fine, but pricey HP-12C
-- KS
Now *that* is a nice auction. It pays off to do a good job.
Interesting to note that his 11c got exactly half of the 12c value:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=58039&item=5881343614
Counterintuitive perhaps?
Edited: 22 Mar 2006, 3:48 p.m.