Amp design logic

I hope you'll excuse my absolute and obvious ignorance...but this is a sincere question.

I don't get why one company is selling a new tube amp for ~$1000, and another is selling one for ~$50,000. What is one paying for? The proprietary circuit design?

Surely if one adds up the cost of the parts, trannies, chassis, etc. it's not worth $50K.

I accept that the more expensive one sounds lots, lots better. But what makes the price so high? Demand?

I think given a circuit diagram from a repair manual, I could eventually build most tube amps from scratch, using the absolute best of each part available. After I learn to solder. For less than $50K, just buying the best cap, resistor, wire, etc. made, for each part, I could slowly build an amp equal to the best in the world. So I don't get it.

What makes an amp worth $50K? It can only be the proprietary tube amp design.

Maybe another factor is the transformers. Each company seems to have their own iron, but that can't be a significant part of $50K?

Thanks, just really wondering about this. And wondering why don't I just make my own? If I buy one part at a time, eventually I can have the best amp there can be.

Jim