I don't know what would happen if you return the item, and are owed a refund less the postage cost. Ebay must have a provision for this. I just know that when I wanted to give my buyer a partial refund, like when the shipping ended up not costing as much as I charged, I was unable to do it if the buyer used a coupon. I had to send the money in a separate paypal transaction. Since there is no indication to the seller that the buyer used a coupon, it was a mystery to me why the refund didn't work until I called Paypal. Now I know that if I try to give a partial refund and it doesn't work, it is because the buyer used a coupon. I'm sure if you did a return, you'd get back the amount you were due, one way or another. Probably when the refund is done through ebay, rather than paypal, ebay has the power to do a partial.