I had it happen to me a few years ago when selling my BMW on Ebay, but it was a day after the aution had finished, it didn't sell at the time and this scammer made contact said the same thing working on a off shore oil rig and said he will send another $1k and could I send that to his shippers, he told me he put the money into my Paypal account and he sent me a copy of the recite, it looked like a paypal official head on it but when I went to my Paypal account of course no money in it at all.
I played along with this scammer for a few days, he even phoned me up to ask where the $1k was etc, but the last call I got from him he was getting angry and abusive, then I told him it was in the hands of the police, funny that never heard back from him again, but don't dispair as I have brought and sold many things off Ebay without any problems, you just got to be on your toes as scammers are every where trying to get your hard earned money and its not only on EBay, every thing I buy and sell go through Paypal and if Paypal contact you they will always go through your account and they address you by your name and the fake ones don't use your name, they address you as Sir or what ever else.
I be a very rich man if I answered althoughs emails saying they have money from a rich uncle or a lotto winnings that I never brought a ticket in, but the scammers know there is a sucker born every day, they just got to find that sucker, just be one step a head of the scammers.
Ashley