[Sangetsu]

There are a couple of shops in Tokyo station which sell JR souvenirs and paraphernalia. If you are in Tokyo during the first or third weekends of the month, you can check out the flea market at the International Forum (located near Tokyo Station). The flea market sells mainly antiques (furniture, clothes, sword guards, and bits of armor), but they also have many other interesting and unusual items. I've seen things like train conductor's hats, and older JR posters and station signs, you never know what you'll find there.

Another place to look is the "Hobby Off" store, which buys and resells hobby items and collectibles. The store near my home has thousands of model trains of every type and vintage, from single pieces to entire collections containing dozens of complete trains.

Good luck, and happy hunting...