I buy a fair amount of stuff on Amazon, and have done for a while. If there's something I need and can afford, and I don't need to touch and see it before I buy, I often buy it there. I don't tend to give it much thought - I've always had good experiences with Amazon and in the rare case of there being a problem, I have found their after-sales service to be excellent.
I recently gave a short concert, and recorded a video of it on my camera. The only problem was, the memory chip was full after 30 minutes, so I lost a good 40% of the performance. There was plenty of battery life left, so I thought I'd invest in chip upgrade. I found some 1 terrabyte chips on Amazon and ordered one.
1 terrabyte - one million millon bytes, on a chip no bigger than a finger nail. When I were a lad, a disk of just 300 million byte capacity was about 12 inches diameter and 8 inches high, heavy to lift up, and they fit inside a drive unit the size of a small fridge. The guy who invented the tech that underpinned them worked for IBM, and he had to take his ideas to Japan, I think it was, before he found anyone prepared to try to make a product out of them. It became, as we know, very successful and he was made an IBM Fellow for some years before he retired. I cross paths with his daughter from time to time; she plays the flute and I have a CD by her. But I digress.
So the chip arrives and doesn't work, and I'm going through the refund process. The chip was sold through Amazon Marketplace, and to my surprise, I discover in the "small print" that the Amazon A-Z guarantee doesn't apply to "digital items", and specifically, not to wot I bought. I'm not sure if that means digital items sold through Amazon Marketplace, or any digital item whatever the source. I'm still going through the refund process so I don't know yet if I've been ripped off or not.
So, whatever, caveat emptor, as always. *sigh*
UPDATE 1 May 2019 Refund received. Cool.