For your reference, I just purchased GX last week with 12k miles for $41.5 + tax. It has every option (KDSS, Nav, REAS, backup camera, 3rd row etc). The cool thing is I was looking for KDSS with tan interior and could able to get it.
Moreover, if I am looking for a used one, I would look for a one which is privately owned and not a leased one. That info can be found on carfax or autocheck. Hope this help........
Edit : Forgot to mention year : 2005.