Certain items carry higher margins than others. Speakers in general have some of the highest margins, while TVs have almost none. In the old days of the 1970s we used to tag phono cartridges with prices like $79, then turn around and throw them into the deal for $10. Still made money on them. Those days are long gone.
There are still items with high margins. That doesn't mean we should begrudge retailers their margins, though. They serve a valuable function that manufacturers are mostly unwilling to fulfill themselves. Without the margin, the dealer wouldn't be a dealer, it's the only way they pull any income. If you like walking into a store and talking to the same guy you bought from, let him make his money.
There are also conditions where a retailer can sell product at or below his cost. Closeouts, discontinued items, refurbs of course, but sometimes an item can be added into a package so that it looks like it's below cost, but probably isn't.
It's useful to keep in mind that deep discount internet prices are sometimes available because the seller is not authorized by the manufacturer to resell their products. Those items won't carry the manufacturers warranty, which some might be fine with, but it's a nasty surprise if you need that warranty. Manufacturers are actively trying to curtail unauthorized sales, so if the price seems too good to be true...check deeper, make sure you know what you're getting. There's also been a lot of "knockoff" product, looks almost identical, but it's not the real deal.
