Core memory does need a refresh after a read, but since it doesn't need refreshing otherwise, I'd mark it as SRAM.

Williams tube memories seem DRAM like enough to me though.

For me, the key take home from the graph as stands is that price per GB right now is about the same as 2020. That seems reasonable, it's more expensive than it was, but only outrageous if you forget what it was like only a short while ago.

But back in 2020, 4GB or 8GB sticks were most common, a few years ago it was up to 8GB, 16GB or 32GB, and now 2x8GB seems to be the most common high-end configuration or 2x4GB for low-end again. If you'd jumped from 8GB sticks to 32GB sticks and back again, it would seem like there was a spike up around 2021-2 and that memory was cheaper now than a few years ago.

I think the main driver for the data is that probably consumers or the market decides on a reasonable price for memory, and people buy whatever they can get for that money. When I had a Z80 computer in the mid 80s, 64KB expansion RAM was about £100. For a similar computer but a few years earlier, a 32KB expansion RAM was about the same price. When I had an Amiga in the early 90s, a 512KB expansion RAM was again around the same price. In the 2000s, a couple of MB was around the same price. Maybe 5 years ago, the market was split a bit and a 4GB RAM was around £60 and 8GB around £120, but maybe this reflects "under $100" as the ideal target. A few years ago, it was similar but 8GB for around £80 and 16GB for around £160, now it's "doubled" in price, it's just back to 8GB for £120 again. But whatever the decade, it seems people are prepared to spend about £100 on memory for an average PC.