Google the lens adding for sale at the end.
There will be a lot of crap but there are some international offers through EBay that do not come when you go to the eBay site and look for the lens.
There are also private offers but one has to be careful there and always use Pay Pal to guarantee you will not lose the money.
The most important thing is to be patient!
You lived all your life ok without it so do not rush into a bad deal and always make a low ball offer to see what the actual deal is.
Good luck
I just saw one at at CatLabs in Boston website, they always ask for a million but this one is almost new.They are asking 4.5K
I do not think it is worth that much but; Who knows?