This isn't my experience at all. In the UK, prices for most films stocks are lower on Amazon than anywhere else. There are sometimes exceptions here and there, but that is the clear general trend.
it depends on how many sellers there are for a given product and how experienced those sellers are on Amazon’s platform. If there are a lot of sellers, and one or two of them are new, then you get a “race to the bottom” situation. In those instances, yes, the price can be competitive with other outlets, and the consumer wins, however, Amazon always takes 15%, even if the seller loses money. If it’s with free Prime shipping, Amazon charges the seller for that too.
Many many new and inexperienced Amazon sellers who think they’re competing on price don’t realize this until they’ve sold everything they have in inventory and get a check from Amazon for less money than what they started with. Then you see them jump on Amazon’s seller forums and complain about how Amazon isn’t being fair, or whatever. They did it to themselves. If you watch who’s selling a given product over time, you often see a new seller you’ve never seen before jump in with a bunch of inventory and want to capture the buy box so they lower the price, and keep going lower trying to retain the buy box until they’ve sold all their inventory, then, surprise, surprise! They disappear. Why? You can’t stay in business with no profit margin. With those sellers their loss is your gain, however it’s not sustainable.
On the other hand, if you watch that same product, over time, you’ll notice that there are usually at least one or two sellers that do not have particularly low prices, and don’t compete on price at all, and somehow manage to stay in business and always have that product available for purchase even though they appear to almost never have the buy box. These sellers also almost never have prime shipping. How are they staying in business? By charging enough to have a sustainable profit margin. Even though they may not often appear to have the buy box, they still get sales based on long term customer satisfaction ratings, fulfillment speed, and shipping speed simply because Amazons algorithms will route customers to sellers that will give the best customer experience, as long as the price difference isn’t large. The buy box price reflects who Amazon thinks is the best seller for you, based on where you’re located, where the seller is located, the sellers metrics, and your purchasing habits.
Of course, if some idiot seller wants to race the price to the bottom and put themselves out of business, Amazon will happily give them the buy box for all buyers because they always get 15%, even if the seller loses everything and dies. The consumer gets a great price at the cost of a business who probably shouldn’t be in business to begin with because it was losing money.
The real price on Amazon is the price those other sellers that don’t compete on price charge. The buy box price is only a price indicator of what you personally are historically willing to pay weighed against what’s currently available in inventory and is different for everyone.