Prices on the low end are going up while prices on the high end are coming down.
This is due to more and more people getting squeezed for cash which forces them to shop at thrift stores instead of on eBay, for example. And once people start thrifting, many of them will arbitrage anything underpriced ("flipping") which serves to close the gap between thrifting prices and the broader second hand market.
In my opinion, it's only going to worse the way our world is heading. I also think that when the boomers start dying off in large numbers we are going to see a glut of the things they collected that younger generations don't care so much about, which will drive prices down. Tools are a good example of this: they have nostalgic value to many older guys, but young guys generally don't have much use for them (because everything is going disposable and/or electronic nowadays) and are content with cheap new stuff when they do need something.
The boomers are a very wealthy generation, so wealthy that they're happy to give their stuff away in old age. I know because I buy their stuff at auction and thrift stores for a fraction of its value. We will see much less in the way of deals once they are gone, as younger generations are having declining standards of living and won't have that luxury. Of course not all are generous, many are wealthy but do not give anything away, rather use their wealth to bid up those collectible markets.
My conclusion is: pillage the boomers while the going is good, but don't cling too much to collectibles as they will eventually be worth nothing. What will eventually matter is preparation to survive coming hard times, and that is extremely difficult to prepare for as it's impossible to predict exactly what those times will look like.
