the premium placed on vintage

I noticed this phenomenon a while back too.

There's a coolness factor associated with vintage rides, perhaps it's the closest thing to a time machine for many of us who had similar bicycles in our youth - in my case, a red Schwinn Stingray. The feel-good cherry on top that comes with saving something from a landfill, plus avoiding buying something new - which took energy and natural resources to produce - may also explain the trend which has pushed up prices of older bicycles.

That's my take on it.