Hi Mike
the C/Y Zeiss Distagon 21 is simply superb. It is unlike any other 135 format wide-angle I have used. However, if you want a really beautiful copy in pristine condition with the highly sought step up hood, I am prepared to sell mine for the right price. The reason I can sell it is that I never use it. My work shooting events doesn't require supreme very wide performance, and causes my gear to get knocked around a bit. As a result I have always been too scared to use the 21 so it sits at home in a cupboard looking minty, which is a tragedy really. I take an inferior lens with me instead, happy in the knowledge that it is replaceable. If I were a serious landscape, nature, architectural or interiors photographer the 21 would be the first thing in my bag. I love the lens, and I am not desperate to sell, so I am asking a serious price which reflects its condition and the increasing scarcity of the lens on the market. My nearest used Contax specialist is listing a copy of the lens at UK£3500, without the hood. My price is UK£3250 with hood. You may see cheaper ones on ebay, but as always with ebay you may not get what you expect.
I am based in London and happy to let you try the lens next time you are over if you are interested!
Cheers