Price of RAM? Bzzzzt!
OK, I just had to do it.
Up into the loft. Pulled out the May 1987 copy of Wireless World (Ok, ok, _Electronics_ and Wireless World). Advertisement from the now long defunct Microkit lists a 1Mbit TC511000 dynamic RAM chip at £32, so multiply up by 8 for 1MByte, or by 9 if you want to be flashy - error corection? who needs it? fro £250-odd per megabyte. You could even get a full PDP-11/73 (with 1MB of RAM) for £4500 in the back of the same mag.
So far as 15 IOPs disks - I don't buy it. At the time I was working for an OEM and our 300MB SCSI drives were 3600RPM, roughly 10mSec access time, so would easily have given you 40 IOs per second.
Too many verifyable hole sin the orginal article to have any credibility.
Postscript: I've long been aware of the "5 minute rule". However, it's incredibly hard to measure the cache life of a piece of data - even using Oracle's extended database stats. In fact pursuant of this rule I've seen mainframe installations where the memory cache was set so large that the time taken to scan it end-to-end was longer than the average seek time to the disk arrarys.