You can't do that.
You offer your buyers 30 days to return their items for any reason.
If a buyer returns an item, unless it is faulty/not as described etc. they have to pay the postage to get it back to you.
Then, you have to refund all of the money they paid you, including postage.
If you are a private seller, using Ebay to sell your own, unwanted items, you do not have to accept 'change of mind' returns. That is an option that you have chosen when you created your listings.
"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)
