The only problem with this is that the average person out there wouldn't be able to understand it easily

I think you're on the right track with this, and I think it could be set up so that the average person could understand it.

An average-quality 128 KBPS MP3 file comes in at about a megabyte per minute, give or take. So charge by the megabyte, say twenty cents per megabyte, and list the file for sale in various sizes in a spreadsheet-like format:

Rush: La Villa Strangiato Duration: 9:35 Price = $0.20 per megabyte.
Low............Fair...........Good............High...........Archival.......Grzelakian
64 kbps.....96 kbps.....128 kbps.....192 kbps.....256 kbps.....384 kbps
$1.00..........$1.50..........$2.00...........$3.00............$4.00...........$6.00

Perhaps La Villa wasn't the best example -- keep in mind that this song is about three times the duration of the average popular song. "Normal" songs would cost considerably less.

(64 kbps is a good compression rate for audiobooks BTW)

This shifts the emphasis away from buying songs to buying bandwidth, which as you suggested in your post is the "right" way to do it.

There could be adjustments made to the cost per megabyte based on the popularity of the band, maybe by means of an audience rating system. Rush might go for 30 cents a megabyte; the latest Metallica release perhaps only a dime.

The downside is that this about doubles the setup time for the music provider, and more than doubles the amount of hard drive space he has to maintain. (I say doubles setup rather than sextupling it because a great deal of the setup is preparing the tag information and getting the music cued up and ready to rip, and this would only have to be done once, then the same song would be encoded 6 times at the differing rates, a relatively quick process that is easily automated.) And if just one person purchased the 384 kb/sec download just one time, that would forever pay the cost of the hard drive storage required for that song 200 times over! (Example above: La Villa would take about 30 MB of space at 384 kb/sec, would bring in $6.00. Hard drive space is about $1.00/gigabyte, or 1/10 of a cent per megabyte. 30 MB thus costs 3 cents, brings in 600 cents, a 1:200 ratio.)

I like your idea a lot.

tanstaafl.