Right now you can get a Free $1 MP3 Credit when you send out a Tweet from Amazon! This expires on March 5th so you will have a few days to use your credit once you send out your tweet.
You can purchase MP3 Albums or a MP3. Prices start at just $5 for the Albums this month making them only $4 after the credit. Or you can get selected songs for around $0.99 each!