For a full album in the store, I pay $8 to $14 for a CD, assuming I buy it brand new from Best Buy or another retailer. On iTunes, I pay $10 on most albums. In a second-hand music store, I'd pay somewhere around $3 to $9 for the same music.
Let's assume (correctly) that I'm not buying a CD for the purposes of ripping it and sharing it on bittorrent.
What am I gaining by using iTunes? Not much. If I ever lose the music I have to repurchase it (from what I understand), which mirrors exactly the issues of losing a physical CD. I'm additionally locked in to Apple as a vendor as soon as I purchase a song. Furthermore, for practically the same exact price, I get music with less quality and more restrictions. How does this make sense? Given that "less quality" and "more restrictions" automatically devalue a product compared to the same product without those problems, why does this business model succeed?
I'm not an audiophile, so CD vs 128kbit doesn't make me upset, but I do like to copy my music around. I have basically three places where I listen to music. My iphone, my house, and my office. All of my music is at my house. Some of my music is on my iphone, and none of my music is at my office. I can stream music from my house to my office, but only if it's in a format playable at my office, which usually means drm-free data so things like mplayer and xmms can consume it.
Only some songs are available in "iTunes plus" - an option to download higher-quality and drm-free music, and nothing I've downloaded today is available that way.
Even if you considered Amazon's MP3 service, it's still a better value to buy the damn CD and rip it yourself. Ripping a cd is a one-click action these days on every platform available, so where's the cost justification in these online services pricing their data at or above what I pay in a store? :(