Hi guys. Today I was offered a Mint condition Pre-ASPH 35mm summilux. It has the serial: 328xxxx which I can't seem to find on http://www.antiquecameras.net/leicamlenses.html The guy has offered an exchange with my Elmarit 28mm Pre-asph + $1200. Would this be a good deal? I really want the summilux, but can't seem to find what it's worth.