Here in Tokyo the 645N is readily available for about $250 or less. And most of the lenses are less than $100 if they are the A series. The ones that cost more are the 35mm, the 45mm, the 300mm and the zooms.
Alan asked about the 45mm. I too have read a few things here and there but had pretty good luck with it. Nevertheless, when a low priced 35mm came along I was more than happy to trade in the 45mm. Now I have the 35mm, 55mm, 75mm, 120mm, 150mm and 200mm.