As reported a few weeks ago, I shut down the Magnatune Internet radio stations because I could not rationalize the $2.50/listener-slot/month cost.
I decided to lower the cost by lowering the sound quality, from stereo-128k, to mono-64k. This reduces the cost by 75%, to $0.625/listener-slot/month as well as letting us support 4x the number of listeners on the same bandwidth. Since we had a fair amount of unused bandwidth after I shut the radio stations down, I thought I'd give it a try.
So far, I've seen only a modest sales increase (under 5 purchases per day) that appear correlated with radio, and most listeners appear to be listening-only, and rarely surfing. But, since the bandwidth is currently paid for, I'll continue giving this a try.
We're around a 1000 listener peak during the day.