A bargain is not necessarily a bargain.
Even buying an item in-store isn't a guarantee that you get what you paid for. Back in April this year, an unknown shopper bought what appeared to be a Samsung 500GB external drive in China. When it didn't work the way it should, he took it to a repair shop in Russia, to have the technicians bust it open, then bust out laughing. Inside was a single 125MB flash drive looping to overwrite previous files when it was full