I have a black Zeiss Ikon 25mm f/2.8 T ZM Biogon lens in mint condition with original box, papers and a B+W MRC 007 (clear) filter on since new that I'm looking to trade for a mint Zeiss Ikon 21mm f/2.8 TM Biogon lens (preferably black). I'll make up the price difference in cash (or trade my Zeiss 25/28 finder with the lens in exchange for cash representing total price difference) for the right pristine 21mm.
I'd be willing to sell the 25mm and finder for the right price if no trades can be arranged.
Happy to provide photos if requested.