Don't buy cables or chargers off Amazon or eBay at all, regardless of price. Unless they are shipped and sold by Amazon - not a third party seller. There is more fakes on those two sites than the real deal.

I always warn the ones I care about the same thing. The worst thing about fake/cheap electronics is not that they don't simply work, but that they might work 99 times out of 100, but the 100th time burn your house down due to failed/non existent surge protection or whatnot. It's easy and cheap to convert AC/DC to nominal rates, but protection from burning down is the hard and expensive part.

I bought some from Taobao. Luckily, my devices are still okay.