Hey, I never used the S.A. The 15 is too much fun! Truth is I bougt a "sack of old cameras" from an antique dealer friend a few years ago for $500. I later found out that he'd paid $25 for the lot at an estate auction! Nobody else bid on it. Everything was borderline pristine. I kept some items and sold off the beat up examples of the same stuff I already had or didn't need. I kept the M2 and M3 bodies, the Rollei35, the Leica cl with the 40 'con, and the 28, 90 and 135 Elmarits, but I rarely use 28mm lenses. After awhile I swapped the 28 with a guy on P-net for the 21 S.A. He felt guilty that it was a black paint 28 and worth more money than he thought so he gifted me with another M2 body.
Since I have zero money in the 21 due to the lucky buys and swaps I'm figuring that it must be worth at least $6,500 if only because it's a charmed lens. With that level of luck attached to it Dan should have no trouble swapping it for a couple of Summilux equipped M8's.
Of course it's capital gains!