Expensive cables are the biggest scam in the world. Many stores sell high dollar items like tv’s, computers, printers, cameras etc. at or near cost, because they know you are going to compare prices. They then make their money suckering you into high dollar accessories (cables being the biggest high dollar accessory to sucker you into). I’m not condoning what he did, but I have a friend that was making a bunch of money working at best buy. He would buy stuff like their 120$ super premium hdmi cables, for 5$ (their cost which is what the employees got them for), and then got his brother to return them for store credit. Sell a tv at cost, then make 100$ profit on the cable.
Further, you had a little ground to argue for better quality cables with analog signals, but with digital. It makes zero difference. A good quality 10$ hdmi cable with give you an identical signal to a 100$ one. The quality will be absolutely identical. Its digital, so either the signal gets there or it doesn’t. There is no quality of the signal like with analog. There may be different standards for the cable, and their data transmission rate (see the links others gave), but if you get the right cable type, the cheaper ones work just as well. Same thing with usb cables (office depot actually has a 60$ ^ft usb cable, and I guarantee I can get a 5$ one that will work just as well). A 15$ surplus cat6 cable will likewise do the same job as a 100$ one. A friend that works at frys told me that they had to start carrying some cheaper cables, because people got wise about the expensive ones, as more and more things went to digital signals.