HDD isn't any different. Peice per TB has been flat for many years. You get higher capacity for Hyperscaler, but those are not intended for consumers and you need to pre book in advance to get them.

SSD price may have fluctuating for the last few years but their cost model are now similar to HDD. And so is DRAM.

Mainly cost to produce GB of DRAM / NAND / HDD are roughly the same for many years. You may get better performance or lower energy usage. But cost hast changed. And all fluctuations in market are supple and demand dynamics, which is why many saw 4TB for $150 in 2023 and thought things will drop soon. But that has not been the case.

We need breakthroughs to further reduce the cost per GB. Although one could argue we have half the cost already if we accounted for inflation for the past 20 years.