One of the benefits of membership in this Board is that it is a truly international one. There are a few active members here who reside in Japan, even more if expanded to include the Pacific Rim nations. If one were interested in an instrument over there, reaching out to someone with local knowledge of what shop actually has the instrument would be simpler and safer. It might also help with the language barrier.
No, I would not use ebay to buy an Alembic, especially not internationally. I do however enjoy that it alerts me to their availability. I like to... browse.
