Let her know that her best option is to onsell the item, as she will be responsible for the initial  $20.00 postage + the cost of return, and also that she will not be refunded the non-refundable paypal charges that have been incurred as a result of the transaction.  So she would only be looking at a refund in the vicinity of  $40.00

Normally buyers will see that on selling is their best option.