text: Somebody got an F/A-18 fighter jet and tried to sell it on there once, but the government found out and made the owner sell it back to them.  I don't think we ever found out who sold it to the person in the first place, but he/she did obtain it legally.  So I guess it wasn't technically "sold" on ebay but I hope you'll agree that my answer complies with the spirit of the question.