Tonight I sent another message to the seller:
"Comparing the item that you sold to me with documented originals, I offer the following evidence that the tompion is not genuine: The cap is bright brass inside, without any trace of oxidization. The patina on the exterior is uneven and clearly has been applied artificially. Unlike the originals, the cap has been drilled through without being tapped to receive the shank. Therefore, the small, round, blued steel keeper nut is not merely a keeper but necessary to hold the entire assembly together. The shank and washer are brass, not steel, and the washer has been soldered, not riveted to the shank. The portions of the shank and washer that are not visible are as bright as if they were manufactured yesterday. Finally, inside the cap where the cork has not been artificially darkened to appear aged, the cork shows no sign of oxidization or discoloration that would indicate that the cork is genuinely old.
"I purchased a reproduction tompion from a reputable sutler some time ago; it is not just close, but exactly like the tompion that I purchased from you. The price for that item was $7.95, plus postage. If you wish, you may refund to me the difference, or $12.43 and I will keep the tompion; or, you may refund to me the purchase price plus the $6.00 that you charged for postage plus another $6.00 for return postage, or $32.38, and I will return the tompion. Please advise which option is your preference."
I know to some it may seem ridiculous to make an issue over just a few dollars, but what dollar value does one put on integrity? I also don't want to waste any more of my time or y'all's so if the seller won't rectify this I'll just report it to eBay and be done.
I remember something that my father once said to someone with whom he had a similar, minor dispute: "I can do you a lot more good than you can do me harm."