You got the nomenclature a bit muddled. Try again with "Zeiss Contax" or "Zeiss C/Y" (C/Y=Contax/Yachica mount). BTW, these lenses are in great demand again because of the DSLR movement, so you shouldn't be too quick to write-off eBay as a potential source. There's an easy way to avoid the so-called "Ninja bokeh" models: only buy a Zeiss Contax lens with the smallest (highest numeral) f-stop marking painted yellow on the aperture ring. There are some exceptions, but this is the safest route until you've done more research.

There is no difference in quality between German and Japanese versions – they were all built under strict Zeiss IQ measures.

The highest aperture number in the MM (multimode) version is green, not yellow. These are the ones without "Ninja" bokeh.

Where all numbers are white, you are looking at an older AE (automatic exposure) version, which has the Ninja bokeh at one or two stops down from WO. Not very obvious in many situations. Most lenses come from both sources in both versions, i.e. AEG, AEJ, MMG, MMJ.

You'll find a great guide here: http://www.reduser.net/forum/showthread.php?92044-Contax-Zeiss-Survival-Guide