I live within walking distance of the Nikon factory in Natori, although I don't think they make cameras there anymore. Japan is indeed a paradise for used photo gear, but you need to be prudent about where to shop. Many stores in the upmarket areas like the Ginza specialize in rare and beautiful items, and consequently have eye watering prices -- think Lemon Camera. Great for looking, not so good for bargains. For run of the mill manual Nikkor lenses it's much better to seek out shops in the outer areas -- try Fujiya Camera off Nakano Broadway, which also has film at competitive prices (a roll of 135 Oriental 400 for USD6).