It's funny how this conversation about the elusive 2/100 ZK is in this thread and at the same time one just popped up in my search for er, another Zeiss lens/
Anyhoo, I don't know anything about the seller I just came across the listing by accident. The seller is in Japan, the seller's name is SAIKORON. I checked out their store and they have a lot of Carl Zeiss / Zeiss Contax items listed for sale.
Hopefully they're not dodgy, not really sure about the price either. Especially when you can pick up a ZF/ZF2 and a Leitax for half or even less than half what they're asking for their ZK.
Tas