Problem with buying second hand canon bodies is you can never be sure how many actuations the body has, unless you can take it in to Canon that it. If you look at my 400D's they're in great condition externally and you might be fooled but they've done 100k+ actuations, probably well above what canon has rated that shutter at.
Buying lenses second hand is a bit easier since you can check for obvious problems - scratched elements, loose mounts and mechanical action, etc. I bought my 300mm f/2.8 second hand from Adorama sight unseen but then I knew they had inspected and rated/graded the lens - I wouldn't extend the same degree of trust to Bob23 on Bid or Buy though.
Like a carpenter with his hammer, I don't treat my gear with kid gloves.