I've had exactly the same thing happen with the last three phones I've sold recently. They were all won by users registered on that day, asking to post to Nigeria, I even received fake paypal receipts.

In the end I blocked non paypal bidders + included terms that said I would only sell to ebayers who are registered far 1month min + had at least +3 feedback and if someone won the auction without meeting those terms then I would ignore the bid and offer it to the next person down who did.