This sucks for consumers. Prices are already way to high for HDs and don't seem to come down anymore. It is as if there is some sort of price fixing going on.
Prices of hard drives historically haven't come down. For a very long time consumer hard drives have been between $50 to $200. What changed over time was the size of the drive you could get for $X. That's still happening, but it's happening a lot slower than it used to be.
With storage its hard to say exactly what its doing, because it won't hold still to be measured. You have to allow multiple variables to change in any stats collected over time (capacity, physical size, speed, volatility).
It seems reasonable to chart the price of some standard capacity (most common?) over time. Is that changing any more?