Why aren’t SSD prices dropping?

[Audigex]

More importantly, why do they appear to be going UP?

• In September 2013 I bought a 128 GB SSD for £80
• In August 2015 I bought a 250 GB SSD for £80
• In December 2015 I bought a 250 GB SSD for £50
• In April 2016 I bought a 480 GB SSD for £90

That seems like a fairly sensible progression. Now, though, I go to buy a new SSD and the price is up massively - a 250 GB SSD is now 30% more expensive than I paid for a 480 GB drive two years ago. All SATA drives, so I’m not comparing SATA to PCIe or something silly

What’s happening here? Is this just bad timing during a shortage, and is this situation expected to change - or is this likely to be longer lasting?

I know cryptocurrency mining has pushed graphics cards up, but this seems crazy - prices are up significantly on 2 years ago.