Ignore anyone that says they are overseas, on an oil rig, oceanographic vessel etc.
The scam is that they will propose to send you your asking price plus extra for shipping your vehicle using paypal. You are then supposed to send that extra amount to their shipping company (usually by Western Union money transfer) as they can't do that from their remote location (although somehow they can make paypal payments!)
The reality is that you are provided a fake paypal receipt (in the form of a forwarded email) and the shipping agent you are meant to send funds to is the scammer
I was trying to figure out how the (obvious) scammer could possibly make money, so I did a bit of digging