Me personally.. I would not ask him for anything back.. Wait until he opens a dispute case against you and then you can post a message in the paypal site there..
Paypal will act as judge and jury and will find the out-come in 3 weeks.. They usually apply the rights to the buyer.. so be prepared for you paypal account to be debited as soon as the resolution process is opened.. if he opens a dispute case..
If he does not open a dispute case against you.. there is not much he can do about it..
Just hope he is a newbie to
Ebay
.. lol