Matsuzaki-san has about 3000 records in stock, he goes to Europe quite often (Germany, Holland) and buys on ebay as well.
You can buy from the website but it is only in Japanese (although an email in English will work).
On the rockabilly planet, RnR Music Garden is quite famous : Ray Campi stops by the store when he comes to Japan, and other artists like The Living End.
When he is not selling records in his store, Matsuzaki-san combs his hair forward and DJs for live events in some Tokyo clubs.
RnR Music Garden
35-4-305 Udagawacho, Shibuya-ku, Tokyo
Tel : 03-3463-0609