it is because amazon introduced charging import fees to the buyer. prior to 2016, i don't remember seeing this import fee bullshit whenever i checked out my purchases at amazon.
P.S. have you tried newegg? it could be cheaper and there is more variety there.
Newegg started an asian online store a few years ago. When I took a look at that time, it didn't have the same selection as the US store.
I've just checked & they have stores which cater to US, Canada, China, & Taiwan. Can get to the various stores by visiting this page http://www.newegg.com/Info/AboutUs.aspx
Scroll down until you see on the left: "Shop by Region: United States Canada China Taiwan "
Sorry I've never tried to order from them & have no idea if they accept orders from Spore?