When something desirable is scarce its value increases.
It's the old supply and demand theory we learned about in school. If more people want something than there is an available supply, the price adjusts upward.
Think of a vinyl album where only so many copies were pressed. Or, consider that only 58 pairs of IRSV speakers were ever made.
Scarcity can even apply to simpler things. Terri and I were skinning a bushel of our homegrown tomatoes last night. We turned those beauties into a delicious tomato sauce we're going to freeze and sparingly consume over the winter months. No one else on the planet has the same tomato sauce as do we.
Thankfully, much of what we as audiophiles value with respect to new equipment isn't scarce. You can grab a copy of a production DAC, amplifier, or preamplifier without much worry about bickering over price. That's not quite as true with vintage equipment.
What we can say about scarcity is that for most of us, the collection of hand-picked equipment, cables, room treatment, and careful placement is unique in all the world. Your system in your room sounds different than mine because of the environment and the choices made to create that system.
What kind of price would you assign to your hand-built creation?