Google Android Market is currently running a special. Millions of songs are currently on sale for 49 cents. Albums can be purchased for as little as 4.99 dollars.
(US only) Celebrate with millions of 49c tracks and full albums for $4.99 for a limited time on Android Market.
— Android (@Android) December 20, 2011
This offer is on for a limited time period. And of course, it remains available in the US market only at the moment.