A decent chunk of that is due to DDR4 production shutting down. If you look to the past you can see that DDR3 prices rose a while after the introduction of DDR4 too. In fact it got more expensive than DDR4, before vanishing completely.

Another thing driving up prices is tariffs and trade restrictions - usually when the main players like Micron, SK Hynix, or Samsung want to stop selling certain chips (say, DRAM at a certain binned frequency), they sell to Chinese manufacturers who are willing to sell slightly lower quality NAND for a lower profit margin.

But that's not happening - the Chinese companies aren't buying up the machines like they used to, because a tariff could easily wipe out their margins. It's not worth the risk.

Add AI to that (not that many are using DDR4), and it makes a bad situation worse.

The AI aspect may get better soon, but the top two won't. I don't think you'll be able to get new DDR4 for a good price at any point going ahead. Your best bet is to buy used if you see a reasonable deal.