Bob,
I live in mclean and I have a 98 GS400 and was thinking about switching to a 2000 + GS430 so I can have Navi and more torque. In my research of finding one I have seen them go from 27000 upto 40000 depending on mileage, condition, and most importantly if you buy from a dealer vs. private party.
Let me know if you need some help.
Good Luck !