Are you buying from a website or someplace like ebay? If a website, you're kinda stuck. If it's from a site like ebay then ask the shipper to include a receipt of the shipping costs to verify the amount you paid.
I was going to buy a pair from the states
I can't buy direct from the store because I live in oz. I was going to use a seperate shipping company ( one where the store sends to them and they ship to me) but the store asks for the size + weight. And a few inches up or down changes the cost significantly