I see nothing of the sort.
(That's not just me being contrary.
)
Prices fluctuate. Have done for a loooong time.
Some things go for a lot of money, then can be picked up for next to nothing, and then again people pay lots for it, next thing you know... etc.
I have been watching this for quite a while (have managed to pick up some things for next to nothing, yes) and don't see a consistent trend either up- or downwards. It appears to depend mostly on the whims of who happens to be in the market, buying. Get a few people who are prepared to pay a lot, and for a while things go for more money. When those people leave the market, things are cheaper again.
A similar phenomenon is created when sellers enter the market hoping their stuff is worth much more than the going rate. Prices then appear to go up. But though they will manage to sell some of their stuff, they generally don't, and disappear again.
Sales figures provided by shops should be treated with due care. In a diminishing market, the remaining buyers flock to the remaining shops. These shops will register an increased interest in whatever they are selling. But that is only (!) because overall that same interest in that type of goods is decreasing.
'Bottom line' however is that you shouldn't trust my view of the market. Just as little as any other "is it just me?" view of the market. It's hardly compelling evidence.