ABSOLUTELY NOT ! no refund, the buyer entered into an agreement when he bought the item, as long as shipping amount was shown, and he agrees, the deal is FINAL, PERIOD.
Sounds like a nickel, and dimer...and some other descriptive words.
Side story, I once sold a couple of boxed double dollar coin sets, start price 1 dollar, shipping 10 dollars. The boxes over an inch thick cost me more than the ten bucks each. for any type of secure shipping, express post, reg. mail, or expedited.
The winning bidder got the coins for the opening bid of 1 dollar, gave me a negative comment for the "high" shipping cost, even though he seen it in advance, and agreed to it. some people.
The trouble with Ebay is, it always takes the side of the buyer.
I repeat do not refund him a cent, that will only encourage him to do it again.
Further more in regard to total actual costs, here in Canada the tax is not shown on the shipping label amount, which for me in Nova Scotia amounts to 15% of the total.