<p>I'll add this to the discussion, for whatever it is worth:<br /> In 2008 I bought a 50 Summicron M Lens (Wetzlar) "Third Version" (I think), in excellent condition from Tamarkin for $799. After about 150 rolls on my M7 with that lens, I sold the lens in 2013 for almost $1,300.<br /> So in terms of several dozen great pictures and the money I made, a fine investment indeed.</p>