Used ones go fro about 400. However, I bought mine new from Popflash. This turned out to be a good thing, since I got a warrranty along with the camera. The lense I got flared whenever it was pointed into a light source. I called Tony (at Popflsh), and he told me to send it to C.R.I.S.S. out west. My camera came back better than new.
I think I paid close to 700usd for mine, but I got extra battery and memory cards as well. When I called Popflash about the flare issue the GR-D II had come out, and I think he said the GR-D was just over 400usd now. So, I would check there before buying a used one.
It is a great camera, and I still have not gotten the hang of all that it can do. But for most people it is very easy to use. It is my first and only digital, so I am still on a curve with it.
Does anyone know if the 40mm lense for the GR-D II will work on the GR-D??