Mike, have a look at 'Camera Jungle' its a Jessops used site, but mail order only, I built my Canon system from this site, they are excellent, no doggie-doo, warranty and often several lenses/bodies of the same type at different levels of condition and priced accordingly, they tell it how it is, with pics of the actual item for sale, some times they publish the shutter count on bodies or will give it to you if you ask them.
Pete