It has a lot to do with increased access as well. I still go to auctions on occasion, and I constantly see folks using their smartphones to research bikes. Now the internet info isn't always right, and it doesn't tell a flipper how to assess a frame or components for damage, but this has forced the prices at auctions upwards and made decent bikes less likely to sit at thrifts (and they used to just sit, 10-15 years back). Most of the flippers want top dollar once they see something similar for big bucks. Hence, prices are forced upwards.

For a prime example of internet mis information and ridiculous pricing info, click here for amusing insights on Huffy Aerowinds. There's a lot of horse hockey like this out there.

In general, the question is if this is a bubble or not. I've noticed some leveling of prices in the last year, but I've also seen an increasing number of riders. Some of them will be interested in vintage bikes in time. I suspect our once cheap hobby may grow (even) more expensive over the next few years. Many of us built impressive collections on the cheap over the years, and I think this will slowly become harder and harder to do.