I see the same scams attempted here in Thailand. The trouble with Amazon, even with Prime, is that the shipping may be free but you get a very big hit by Customs Duty fees. Sometimes nearly as much as the item price, so it just isn't worth it.
What has worked out much better for me (and my wallet) is making connections with a few of the local shops. They import in bulk and are very fairly priced. 1Kg spools for about 18-20 US. The US brands are the only ones that are hard to come by, again, because the duty fees are so ridiculous. (In most of Asia, US=U$)
The upside is that the filament they import here from China is quite often produced in the exact same factories that produce most of the big name brand filaments and the results are identical. Since the local shops are also enthusiasts and printer jockey's themselves, they stick with the good quality imports as they find them so the overall stock is very good.
I can't say for sure, but I would imagine that was the same situation in Taiwan, and Japan shouldn't be much different if you can avoid the scams. At this stage of 3D Printing, community is key and having good relationships with fellow enthusiasts and supply chain is critical. Most of the manufacturing of the printers themselves, and the PLA, ABS, etc. is done in Asia, and you would think those of us here would have the advantage, but at the consumer level it doesn't quite work out that way. Most of the information, technology, software, etc. is in English language, so it really levels the playing field.
I would love to know more about the 3D Printing situation in China if anyone has insight. Most of the clones/replicas, and even some of the name brands are produced (and sold) there, and you can spend all day browsing filaments on sites like Alibaba too. As a nearby outsider looking in, it would seem that a lot more mainstream there.