Does anyone here own a EF 400 f/2.8 L? It's the non-IS version. If so, what is a ballpark price for one that is used? A person has loaned one to me to try out this weekend in hopes that I might buy it. Asking about $3K USD for it. I tried B&H and Adorama for a price check, but nothing came up. If it performs as well as its suppose to, I want to make them a fair offer.