The buyer is no newbie to eBay. His feedback is 6948. He is no idiot but he is a first class A-hole. I'm surprised that he doesn't have any negative feedback himself!!!
Refund his money and shipping and tell him to take a hike if he insists on screwing you out of the costs for grading. How nicely you tell him that, I'll leave up to you.
I'd lose the Cobb image. It has nothing to do with the item you were selling. Also, there is no need to put "TRIMMED" in the title. The title line is limited. That's why we have a description area for the details.