Here is an updated chart of the average price per to purchase an album at Magnatune, showing 3 1/2 years of data.
The average price fluctuates a lot, so I'm presenting two charts, so you can see the general trend, and the variation.
Here is a moving-30-day-average chart:
and the same data, but on a moving-10-day-average so you can see the fluctuations:
and finally, the long view, with a 90 day moving average:
this has always fascinated me: people pay a lot more for the music when they're getting a CD, and the voluntary price is rising (people pay almost $2 more for music on a CD!):