No doubt there's a lot of goofiness in the guitar scene. But from a strictly price standpoint, it's nothing like 'high end' audio. I think it's because most players just don't have a lot of money, and if they did, they'd rather buy a new guitar or pedal than an expensive amp.
The link you mention, Alessandro (which I was not familiar with), is not out of line for a hand built product--just on price alone. Their Princeton mod (which I presume includes a 'regular but used' head with the deal) is priced at 2K. A new Princeton is $1400.00. So his upcharge for hands on work is not unreasonable. If you have to supply your own amp, then it's a different story. Whether his 'mod' makes any sense, is another question, though.
Crossbread is $2400.00, which is quite a bit less than, for example, an upper end 'mainstream' Mesa head.
When you get the his AZZ model, it's 'custom order', and then he's asking big money. Probably very few are sold, which is why it's a 'build on demand' product.
Nutball guitar stuff extends farther out from whatever you expect from hi-fi weirdness. I don't know of anything comparable to 'cable risers' or 'magic bricks', or special power plugs in guitar world. Maybe it's there, but I just don't know about it. Instead, you get folks arguing about whether nitro 'breathes' into the tone, whereas a poly finsh 'constricts' tone. Which is pretty funny, when you see 'relic' guitars with the finish almost completely sanded off. I guess those resonate best!
I've mentioned it before, but somewhere Les Paul once quipped that people 'listen with their eyes'. So true.