As a counterpoint: Most people I know go to Amazon 100% for the prices. Often they will actually visit a brick-and-mortar store first to browse in person (page through a book at a bookstore, even try on shoes at a shoe store), and only then order on Amazon, once they've decided what they want. Amazon adds nothing here in convenience or service. The most convenient option would be to just buy the item you already physically have in your hands, which means you'd get it today, and not have to deal with UPS missed-delivery bullshit. But Amazon gets the sale because they win on price. Or at least used to!
counter-counterpoint: I bet a large portion of the people you're talking about are genuinely price conscious consumers trying to make the most educated purchases they possibly can. I doubt these people would be the same type that blindly buy an hdmi cable at a 20% markup... how simple is it to compare prices these days online? If you're traveling to a book store then buying through amazon I would bet money that you're probably going to price check that Amazon branded hdmi cable.