Personally I wouldn't have allowed Paypal as there are a million and one ways to scam a seller with it.
As said above, make sure you write down the serial number, and send it tracked and signed for.
Even then there are still ways around this, I guess that's the chance you take.
As said above, make sure you write down the serial number, and send it tracked and signed for.
Even then there are still ways around this, I guess that's the chance you take.