If your lucky you might get a seller who is prepared to run at a loss.

Note if the return arrangement is not going through the official return process, the sellers ebay  sales fee is also not refundable.

So on top of the return postage, they may also want to withhold their original postage cost + ebays fees.

I see in your last post, that you are aware you have no protection if the return is outside ebay.  As far as paypal is concerned, your transaction was with ebay, not the seller.  So if the arranged return goes wrong, and you tried to claim via PP, then ebays response to PP would be that the  only record of return, is the one you have cancelled.