Your seller clearly accepts paypal on thier listings, so they cannot refuse. If you have already purchased, just pay by paypal, if you need an invoice to pay, email the seller, advise them that you will pay via paypal as soon as the invoice is recieved, and if they open a dispute for non payment, you can let ebay know that they refused to accept a paypal payment even though it is an accepted payment method on thier listings.
