Only way to know what it is really worth in your area is throw it out there on craigslist farm + garden and see what happens. And no, dealers don't really give anything on trade-in for used lawn tractors.
FWIW, I paid $220 for a 2164 with 2100 hours as a parts source for my 2135. The running board sheet metal was completely rusted out. Reason was, it had been used as a salt spreader, so the PTO clutch had never been used and the Kohler 16hp started and ran perfectly. Either the PTO or the engine or the transaxle would cost me more to buy than the complete running tractor.
jack vines