Over on our kissin' cousin site, MacUser.com, my colleague Dan Moren remarked that he's in the market for a good search engine that allows him to compare prices of music downloads at Amazon MP3, Wal-Mart.com, and the iTunes Store.
I think that's a great idea and I'm a little surprised that such a thing hasn't crossed my path. In the meantime, however, I can offer a couple of tips for more easily shopping at these outlets.
As for Wal-Mart's MP3 download service, a web clip can come in mighty handy. While using Safari, navigate to a page such as Wal-Mart's Top Albums page, choose File -> Open in Dashboard, and drag a selection around the Top Albums pane (being sure to include the scroll bar). Add this as a Dashboard widget and you can easily browse through Wal-Mart's top albums to glean an idea of what they're selling for.
Amazon MP3 doesn't include windows with scroll bars so a web clip isn't much help. (Though a web clip is a help for making a widget of the MP3 Daily Deal.) However, with Alien Orb's free Music Store Search widget you can enter the name of an album or artist's name, press Return, and both iTunes and your default browser launch--each displaying the results of your search--thus allowing you to quickly compare prices.
Speaking of the iTunes Store, if convenience is your goal and you like free stuff, it's worth your while to bookmark any of the websites that list the latest free iTunes Store downloads. They include the Free iTunes Download blog, Get Free iTunes Store Downloads, and Free iTunes Downloads. Or you could always check the Free On iTunes page within The Store when the mood strikes.
And while we're on the subject of "such a deal" be sure to take a look at Dealnews.com's MP3 Downloads Deals page. This page alerted me to the free ECM Touchstones: Digital Jazz Sampler from Amazon MP3 along with some other impressive bargains.