I have used KEH and MPB in trading my lenses for an upgrade and both outfits are good. It seems that MPB has lower prices on their excellant and LN- equipment. I know your selling to them and getting wholesale prices which are usually around 50% of the used retail price, but much less hassle than using Craigs List. I checked my lens inventory and 95% of my lenses are used. Due to the people who have to have the newest equipment, then sell quickly leave a lot of wonderful equipment in beautiful condition for us penny pinchers.