They pop up every so often, this guy has one. http://harsinoliver.000space.com/tractors4sale.html
A quick glance through the ads here has:
39 standard in CA for $1950
I don't keep an eye on them really, but a quick search showed up a few auction results in the $2000 to $4500 range with most under $3000.
one sold dec 6th for $3900 here:http://www.wiemanauction.com/machinery_auction_info.php?machinery_auction=16 This post was edited by Paul Searl at 13:32:35 01/28/12.