Yeah, gotta move fast on used Deeres sometimes.
Either the 4310 or 4410 would be a good choice. Good power and reliable.
Although I'm a gear tranny guy, I'd also go for the 4410 since it has turf tires. Turfs are great for mowing and better then R4s for snow plowing.
For comparison purposes, I paid $13500 for my 2000 4400 with turfs (R3 tires), 430 loader and an 84" RFM. Mine had 804 hours on the meter and has the Sync-Reverser and less electronics then either the 4310 or 4410. This was when we lived in PA about 3 years ago...a few miles SE of York, BTW.
As far as your offer...can't hurt to see what kind of response you get when you offer $14K.