As computer tech has changed so much over the last 25 years, would be an almost meaningless quest. One best left to a PH'd dissertation.
Back in 1985 you could build an IBM XT clone with all the port cards and 20MB of Hard drive, 640K memory, and NEC V30 8086 clone cpu, and an EGA card for about $1600.
$1600 today will buy you a banging computer. As things have become standardized computer parts have become commodities.
To do a proper study you will need to break down the items buy cost per megabyte/megahertz referenced to a fixed point monetary constant.
I bet google would help on both. Most libraries just don't keep periodicals for any length of time.
For a rough guesstimation the system you can build today for $1500 at todays dollar, is really about $150 in 1980 dollars.
The only thing on a computer that is not acting like a commodity is the Microsoft OS and Office Suite that you put on it, they both keep up with inflation.
One excellent resource for this would be The Computer Shopper, it was basically a mail order catalog before internet shopping made it irrelevant.