I looked for a "unique" phrase in the text and Googled it to see if it showed up elsewhere...
i will like to add $US200 to your final price for you to keep
This guy buys a lot of stuff for his father. Best son ever!
http://www.scamwarners.com/forum/viewtopic.php?f=6&t=85821
http://www.riverdavesplace.com/forums/showthread.php?118305-Scam
EDIT: This is the classic "overpayment scam", but using Paypal instead of a paper check.
The basics of how it works (if it hasn't already been explained 1,000 times in this thread) is that the scammer offers to buy your item and pay you an additional amount over the asking price. Even though he claims this extra $250 is yours to keep, he'll either find a way to ask you to give this money (or an additional amount of money) to his agent/mover or back to him (via Western Union). More than likely no one will ever show up for your goods, because this guy is in another state (or country even), and he'll just ask you to wire him the "overage". If you do go ahead and send him any money, you'll find out that any money he sent to your Paypal account is now reversed (due to a chargeback or fraudulent charge) and you are out the amount of the "overage" that you wired him.
TLDR: If someone is willing to pay over the asking price, make it (the overage) in cash. Heck, make the entire payment in cash.