So out of curiousity, (Stardock) does the whole box qualify as Package or Large Package? What are the dimensions? Because if it only qualifies as Package (Max. length 24", max length, height and depth (thickness) combined 36") which it sounds like it would, then you guys really need to go back to your USPS sales person and get them to give you a realistic rate - the online calculator at usps.com says that's exactly what a person off the street would pay (for Priority International, since apparently First Class isn't available for anything over 4 pounds), which is a bit slack of them.
(On a side note, why does the Sins CE show up as $0.00 in my Stardock Store account?)