Yahoo Auction Japan is basically Japan's version of ebay. I've seen guitars on Yahoo Auction Japan one week and the same guitar on ebay the next. There are several people who live in Japan, buy guitars, and make a living (or suplement their living) selling to the US, Canada, UK, Austrailia, etc. Not a bad life really.
Most sellers on Yahoo Auction Japan do not ship internationally, so unless you know someone in Japan, you can't bid. Still, you can look and get an idea of what the guitar goes for in Japan, (or what price the international seller paid for it.)
Here's the link:
Yahoo Auction Japan
Most English will work, however, here's Matsumoku in katakana: マツモク
Copy and paste that for Matsumoku searches. Not all sellers in Japan know that their guitar was made by Matsumoku, so check the brand names as well (in English.)