I'm not arguing against Bottlehead stuff. They make great gear. But again, there is perceived value, labour required, and zero-casework (tally up the hours and make a nice case, that Crack is suddenly a $1k+ amp). Building from a finished kit with the benefit of economies of scale and not needing to spend all the time sourcing individual components is also vastly different from DIY'ing from scratch, especially if you're making something up entirely.
Since the conversation was briefly veering towards commercial prices and markup, I just want to point out that yeah commercial prices are high exactly because the designers/manufacturers spent a crap ton of money and time experimenting and blowing stuff up, sucking up huge outlay costs for production, shop fees/rent/distribution/wages, and trying to make some pocket change on the side.
Yadda yadda, some values are better than others. But yeah, some DIY can be great value, but I would say most of it isn't unless you're in it for the long haul, have ample spare time, and just put things into very simple boxes.