- pick up sellers with good credit.... usually they are honest about the items, good and bad. some sellers will give very detailed descriptions about the scratch, dings, marks of the lens which make me trust them more. some sellers even have return policy and the price will be a little higher.
- ask question before u bid ...
- i have purchase some manual lenses from eBay, they are all located inside US. the lenses show any tear and wear with years of usage, but i found most of them are pretty good optically.
- check the mount for Canon.
- be patient when bidding ....
good luck!