Hi! that ebay offer is mine. Basically cost that much because of:
EMS shipping: like US$30, but you get insurance and tracking number, cheaper alternatives exist
Weak dolar-yen conversion
Ebay fee: if you want to do transaction outside ebay, costs 4% less
Actually, I don't get that much on every keyboard, but shipping+ebay+paypal take a lot of cash
if you are interested, well, just let me know
I almost got the money for my own HHKB muahaha