MC quoted me $19.80 for each set as per the email I got. I have to see my credit card after this though.
However, under the postage and fee section of the Customs Declaration and Dispatch note, it states it cost $17.30, which sounds about right for priority. But the little USPS sticker at the top of the box states $2.90. Clearly something doesn't add up here.
But at least I didn't get nailed with duty tax as the value of the sets wasn't written on the customs note.