Agree completely! Maybe I can add some of my own experience: I tried to cut down costs and buying a cheap keyboard (20EUR range). I was back in the shop the other day, because 2 of the keys were already stuck. I returned the keyboard and got a "quality" keyboard for 50EUR, which has a way better feel, btw.
Unfortunately even the life of keyboards and mice is not infinite. Not because they break (although mice tend to break, esp. in the hands of my father ;-)). No, the reason is the change of plugs which happens every few years. The former DIN plug, changed to PS/2, changed to USB. Same for mice: serial, PS/2, USB. Admittedly, you still can use PS/2 with USB using an adapter. The change of motherboard standard to ATX prevented the use of cases and power supplies a few years ago.
Not only cases, keyboards and mice are expensive: I suspect that many companies get rich by selling cables at ridiculous prices. Just recently I bought an ATAPI UDMA/100 cable, round profile for 7 EUR. The flat cable would have been 2 EUR - a reasonable price. I only bought the round cable because the employee told me it was shielded (which it was not). It's simply a flat ribbon cable with a few cuts between some conductors and some plastic tube holding the stuff at a round profile. Extremely low tech - but sold at 3 time the price.
Concerning cases being expensive: sometimes I think that generally big things cost more. It may be simply the raw material costs (need some kg of steel or expensive Al to make a case). It may also be storage or transport costs for these bulky items. I also suspect that for HiFi audio equipment the cost of the (very nice) cases is not negligible.
Generally I think that we are quite lucky with the prices of high tech gear. A graphics card which costs just 200EUR, a DVD burner which costs just 50EUR, is amazingly cheap! I am working in a research lab at university and the prices for non-consumer electronics are waaay higher. We bought a DC power supply 0-250V, 0-16A, which costed 3000EUR. This was the cheap option! It's just a rack mount box with some analog electronics. If you buy a oscilloscope with a bandwidth above 500 MHz, you have to think in the range of several 10k-EUR. Some of them have actually a windows PC built in. Some years ago we bought a PCI card which can measure the dime delay between logic pulses with an accuracy of 0.25 ns. It costed 60k-EUR (including a dual Pentium-III PC as a "goodie"). Admittedly probably only a few hundred of these cards are sold worldwide, if at all.
Compared to this, the price of consumer stuff is really ridiculous low. Obviously the economies of scale kick in here quite efficiently.