I have put this up for sale another time, and then changed my mind, but I am not using this. I sold all of my M mount cameras and have six 50's to use on my NEX.
This cron has really nice glass for a collapsible cron. There are cleaning marks, but minimal. The body has cosmetic damage and is a user. It was like this when I bought it, but seller didn't mention this damage. I have included photos from all-around so that you can see the damage. Focus is smooth and it clicks into all detants.
If you want to use this on a NEX, I can sell you an adapter. This is an opportunity to try Leica glass at a reasonable price. $450 plus $20 shipping to your US location. Canada at actual cost.