I've written before about used goods in Japan. They just aren't that common. However, the thrift shop movement has grown a bit here, and flea markets have been a part of Japanese culture for a long time. Known as the largest flea market in Japan, the Setagaya Boro flea market is held twice yearly, in mid-December and mid-January. This market dates back to the sixteenth century!
I probably could have bought more, but as always funds were limited. I did get quite a few things, though:
The Setagaya Boro-ichi flea market takes place 9 AM to 9 PM on December 15-16 and January 15-16 each year. Access is best via Setagaya or Kamimachi Stations on the small Tokyu Setagaya line. Just follow the crowds south from the stations.