Not for nothing but I have a pair of latches on the way from UK to here. They are small, would fit in a 4" x 4" x 9" long box and weigh less than 5 lbs. Freight is over 50 bucks.
All I know is there is no rhyme or reason to shipping costs. If you want to see really dumb prices, do USPS outside of their flat rate stuff. We get folks ship stuff back to us in a large flat rate box that they neglected to stick under the flat rate charges for reasons I can't figure out. 38-40 bucks in postage on the label stuck on a large flat rate box that is roughly 20 bucks to ship.
If you told me I could get a shifter size box to the UK for under 40 bucks, I would have to do it to believe it.