Sorry for the little OT.. just to tell you how wonderful is this project and how I consider myself very fortunate to have begun to study mechanical keyboards just a couple of weeks ago. I've got the impression that this diy craziness had just started to move not too long ago, maybe that the cost of cnc and pcb printing can explain it.
I believe the keyboard enthusiast community first started in 2006 in Korea, so you're really not far off at all in the assumption that custom boards did get popular only recently.
It's also a matter of fact that unlike many other PCBs, the ones for keyboards can be used for only that single purpose instead of something like an Arduino or a Raspberry Pi.
Therefore, the demand is lower and it's more expensive. Yes, demand should increase prices, not decrease them, but at such low levels such as what we see here, it costs are extremely high compared to what makers have to initially invest, thus prices need to be raised.
I hope I didn't misunderstand what you were trying to say.
