Recently i have had some trouble when selling my xBox on eBay. Noteably from an international buyer who claimed they lived in the states. The buyer used the buy it now option to make the claim on my xbox and then asked me to find out the cost for sending the system to Nigeria, this was the start of a snowball which started a few bells ringing in my head. I called Parcelforce to find out the cost of this which was going to be basically £270, I nearly died there and then. The guy i spoke to then went on to inform me of foreign buyers wanting things sent to Nigeria and 90% of these were eBay targets. What the scammers had done was to make up fake PayPal emails to send to eBay users after purchasing items, and sending them as to say the person had x amount in their PayPal account which was being held aside until shipping details were sent to PayPal so they could give this to the buyer. Now obviously the only way to get a tracking number is to send the item, you then think you are going to get your money, but you don't. Your item is gone, you are out of pocket for the delivery and you have no money to show for it.
Here is the cut down. If you get an international sale and the email you get says you will get the money after tracking info has been sent, report it immediately, to both PayPal and eBay. PayPal will never ask you to give shipping details, and they will never hold a payment for a sale, once the pay button is hit and PayPal inform you the money should be in your account if not, likely you are being scammed.
Be ever careful.