We should be measuring it by the amount of RAM in a typical household PC in 1987 and today.
Even though a "meg" of RAM costs less than 1 cent today, I can't do anything useful with it.
Even if we are generous and buy a whole $1 of RAM today, it only gets us 150 MB of RAM, which, while infinitely more useful than 1MB, is still completely useless for running a modern OS/Browser.
What does your math say about that?