Today's new Mass Effect 3 Resurgence Pack expansion is supposed to be free, so don't accidentally buy the 320 Microsoft Point version.
The official BioWare Twitter feed delivered that warning this afternoon:
Please DO NOT purchase the 320 pt. 'Resurgence Pack' consumable on XBL dash. This was erronously uploaded & we are working to take it down!
Stick with the free version, people. The Resurgence Pack is supposed to improve your multiplayer experience with two new maps, new characters, new weapons and more.