easy kyle!
either 1 DEMAND a recalc, send him links from USPS sites etc, that SHOW shipping price (global priority is best, roughly $7-$9 for 5 cards I think?)
or 2, dont pay the fucker, and leave a negative with ur reason.
u could also (I think) contact ebay but I think postage is someting that they are free to decide themselves how much to charge...
but he's takin u for a ride if you pay that for 5 cards bro!!