Whenever I read about vintage stuff or boutique stuff trying to hark back to a vintage product I think of that dude from Raiders of the Lost Ark.
"Look at this [holds up a silver pocket watch]: it's worthless. Ten dollars from a vendor in the street. But I take it, I bury it in the sand for a thousand years, it becomes priceless! Like the Ark. Men will kill for it; men like you and me."
Does this fit in this thread? Probably not, but it's Friday
I'd disagree with the analogy. The price for any object is set by supply and demand. Of course, the interaction of demand and supply is a bit more complicated than this, but bear with me.
In the case of the old watch, it is valuable (assuming that it becomes a collector's item, as lots of old things aren't) because supply of very old watches is limited. They are rare.
Most vintage guitars, amps, etc. are really not all that rare. Thousands were made not long ago, many or most survive, even if they are not all factory-mint.
What drives prices for guitars and gear is demand more than supply. Now, one could argue that demand for vintage gear is largely an artifact of the baby boom generation trying to buy the guitars their heroes once played and otherwise to relive their youth, and that prices for such gear will fall as the boomers get older, but that is another discussion.