Probably not.
Whether you say "No returns" (which is not the same as 'no refunds' by the way) , your Paypal agreement trumps that.
Is eBay telling you that you have to pay for the return shipping? That's something new, and I'm not clear on when it is required.
Normally, the unhappy buyer is required to return the item for a refund. If you do not refund when the item arrives , and the buyer is supposed to use Confirmation of Delivery to be able to prove that, PP will refund and come after you for their money. There is other fallout for you.
The 'buyer pays for return' is a longstanding part of the return for refund process. It prevents many scams and buyer remorse returns. But buyers don't like it , and frankly some sketchey sellers would use it to prevent refunds. for example, it costs $40 or more to return the smallest item to China with Confirmation of Delivery.
