4tb drives have been around for about 4 years so they should drop to about $99 (or less) in the next year. That's about where it would need to get to on this black Friday for me to jump and buy one. Lowest I've seen 'em is $109 - $119. The problem with dropping prices is that the low end of the marketplace still keeps demand up for low end parts (aka the cheapest). That puts "HIGH" demand on 1tb drives. So, instead of it clearing out at $25 for that 1tb drive, they can charge $40..
and that puts 4tb drives in the $120-$160 category. When consumers start buying 2tb+ drives and shunning the 1tb drives.. then the market can discontinue the 1tb and charge $40 for the 2tb drives shifting everything higher. Do we buy 1gb flash drives anymore? Not really.
As for ddr memory.. I should be able to buy ddr3 8gb sticks for $40 by now-- not $75+ These mfg's really "STICK" it to the consumer with market manipulation. And there have been no long term serious disruptions in the last 5 years of production.
BTW, 8tb drives are enterprise and likely to have a hefty price tag. At least HDD makers drop prices relatively consistently.. you can't say that of any other PC parts niche.