I like building things, so I'm making my own keyboard. I decided on a switch type. I like a strong tactile switch so MX Browns are too soft for me so I'll pay a bit more for something that suits my taste.

My PC is in the living room, I like having a pretty living room, so I'll pay a bit more for a pretty keyboard case, a pretty rotary encoder and pretty keycaps.

I'm French and the problem to me is that the hobby of building custom keyboards is increasingly popular in the US and in Asia but very little of it is European. This means few keycap sets have the big ISO enter key that doesn't exist on ANSI keyboards. Pretty keycaps are expensive. Shipping to/from the US and Asia is also expensive.

I also use a non conventional keyboard layout (Canadian Multilingual Standard) which has small differences with more standard layouts and though I can type mostly without looking at my keyboard, I still look a it sometimes and it's confusing to have something completely different printed on the key. I've started working with blank keycaps but those aren't much easier to find. Especially in some profiles. (You can have an idea of profiles here : https://www.keycaps.info/stack)

Another factor to the cost is that a lot of the parts are produced for limited runs. I'm not exactly sure how it's organised but a designer submits a new design, if enough people are interested they order a bunch of them with a little extra but they can't easily buy a lot of stock to keep selling. I feel like a lot of the designers do it a side thing and can't afford to invest in it.

Compare it to cars, where people will buy extremely powerful cars, with crazy interiors and using enough petrol to power a small country when a good old second hand Voxhall would be enough for their needs.

It was an interesting endeavour-- designing a PCB, mounting plate/casing, sending them out to be be drilled, soldering it all together, configuring QMK firmware. It's the order of something like assembling Heathkit audio gear was in the 1960s-- the finished product is on tier with a good quality commercial product, but you also get complete control over any substitutions and customizations you like.

Unfortunately, due to low economies of scale, I paid about $500 for the board.