I would not say it was unreasnable to ask for you to foot the postage cost of it going out if it has arrived faulty.
I would calm down a little and await it's return if it is not faulty then take it up with paypal and the buyer.
If it is faulty then refund his money and move on.
But this is the sort of thing you need to plan into your profit that you will get returns and as a buyer (and i am sure you will agree) if you bought something online and it arrived faulty would you want to make sure you are not out of pocket by a penny ???
__________________
Reliable Computer Dropshipper
www.pcdropship.com
Windows 7 Software And Netbooks Now Available