You can still pay via paypal and get paypals seller protection, it is not just available for ebay items. Just go to your paypal page and click on 'send money' then click on 'pay for non ebay item' you put in the buyers email/paypal address and the amount , you can add a note saying what it is for . Then just click on 'send'
Alternately ask the buyer to send you a paypal invoice for the correct amount and saying what it is for, then once you have the invoice just click on 'pay' and it's all done.
Paypals seller/buyer protection works on ANY item sold using paypal NOT just on ebay items ! , few people seem to know this !