I’m a frequent Amazon purchaser, though not quite as impressively as some of the posters here (and I’ve never bothered with Prime, mainly because I just don’t have that kind of volume). What I wanted to add here, as so many have discovered, is watch out for prices. They can vary between good deals and rip-offs, and for some third-party sales, the rip-offs can be extreme – basically just predatory pricing on the basis that the buyer either has to have it (as often seen during the pandemic) or just doesn’t realize what a rip-off it is.
I’ve seen some oddball computer components (things like obscure adapter cables) being sold for many multiples of what I could get the exact same thing for at a local computer store. And while I haven’t seen Amazon’s own prices being so outrageous as to be called a rip-off, they sometimes do vary quite a lot over a short period of time, much like a volatile stock. Amazon obviously has pretty complex and rather bizarre pricing algorithms that are always in operation.
If I’m buying something even moderately costly, and I’m not particularly in a hurry, I tend to watch the price fluctuations much like I watch stock prices.