For those of you new to this perpetually unfolding saga of prohibition, let's recap: The R4 is a flash cartridge for the Nintendo DS, which allows users to play homebrew and/or pirated games on their handhelds. You can probably guess which usage was more common.
So far, distributing the R4 (and similar devices) has been banned in Japan, France and the UK. Additionally, Amazon and eBay have discontinued sales of the cart at the behest of Nintendo. Australian-based distributors of the cartridges have been successfully sued by Nintendo, and a man in the UK went to prison for a year for importing over 26,000 carts.
So, if you have to run an illegal import/export business, take our advice and shift away from the R4 and refocus on something less dangerous to work with, like cursed Egyptian artifacts, or mint-in-box time-traveler's bones.