You do have the option of not getting the item back.
Ebay make a standard charge for a tracked small parcel up to 2KG - the item has to be returned tracked as the buyer needs proof of delivery back to you.
If it's a low cost item, it is sometimes more cost effective to just refund and tell the seller to dispose of it. Even if you provided your own label, you would have to pay for some sort of tracking.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)