Obsidian and other expensive / high-end cases are cheapest in the US, sometimes half the prices in South Korea.
I paid about US$160 for my Corsair H100 liquid cooler. Look at the price listed at the official Corsair website. South Korean VAT is 10%, so VAT alone cannot add $40. Its current South Korean retail price is around US$175.
If you seriously consider the value and cost of human labor, those things are sold at ridiculously low prices in the US. If I ask local engineers to build custom cases for my PC's and ODD/SSD/HDD's, a much inferior case would cost more than an Obsidian 800D to make.
But low-end cases are sometimes still cheaper here - cheaper than a typical Corsair fan - because 'handling fee' - the kind of fees Amazon.com always seems to add even for one copy of massmarket paperback book - is usually disregarded and most orders take place within 100km of shipping distance.