It's often been said users can buy literally anything on eBay and this seems to be borne out by reports that even sensitive US military kit – including fighter jet parts – are available on the popular auction site and others. 

Investigators bought a range of US defense force items on both eBay and Craigslist, and received them with no problems.
It is suspected that most of the items have been stolen. Others could have been sold by individual soldiers who had been issued kit and were selling it for personal gain.
Many of them, like F-14 fighter jet parts and nuclear biological protective suits, would be highly desired by Iran.