Used Race parts are always, AS IS. I have sold many and bought many. You get what you get, unless they are broken already, there is no recoarse. Who says he didn't run them and didn't like them?
Just the fact that you show this much concern to make it right, you are on the up and up.
It's always the guy that beats you up on the price. Tell him to box them up, and he pay's to ship them back. Then refund all the money MINUS the shipping to and from.How much more fair is this?
Then resell them on Ebay, and get more money from them. I have sold sets like this for $500.00+
Hang tuff, I would buy from you any time