Need Opinions on Ebay sale

Heres my story, I had my 360 redone last summer, it is now a 412 stroker, took all the used parts that the engine shop gave back to me, one of the items that I had was my used mopar standard adjustable rockers, shafts, spacers, and pushrods, mind you they were on my engine and working, I put them up for sale on Ebay and a guy bought the whole works for $50.00 plus shipping, this was in April, I had pics of the parts and I put as-is and no returns, they were shipping to california and then to Australia, now 3 months later he sends me a email telling me they are unusable (worn and scoured) and expects me to do something as he feels he got a raw deal, these were in my old engine and it ran fine, I just wanted a stroker so i had mine rebuilt, I trust the opinions on this site so what do you all think I should do?? thanks.