Well, the distributor wants his cut. So does the dealer. When they say 40% markup, they mean 40% of the selling price, so it’s actually a 66% markup. To be fair, each has his own costs and it’s not all gravy, especially the retailer.
Then there is marketing. Only a few can get by with no marketing at all. But they have proprietary designs and proprietary skills and proprietary parts. For example, there was only one source of small exotic platinum magnets with a highly uniform magnetic field. They were made in quantity for MRI machines. When the factory closed, one alert client scooped up the world supply. That was Koetsu, so they alone have platinum magnets.
Speaking of Koetsu, their top cartridges also feature aged rosewood bodies, or stone bodies (which are prone to shatter during manufacturing), and diamond cantilevers. Then it is fair to say that the highly skilled labour isn’t cheap, and that many examples, from parts supplied to them to finished product, are substandard and need to be discarded.
We all asked the same question about HP tubes, back in the day. Thing was, we could buy a 6922 (tube) for $3, but a 6922 from HP was $30. Little did we know that the HP tube was a bargain: it was later said that HP bought the tubes by the pallet and discarded 98% straight into the dumpster. The same MAY be true of the best cartridges, not that we’ll ever know.
So you pays your money and takes your choice.