MasterVG71782 on 17 January 2011
Both LBP2 and Mass Effect 2 have $20 credit offers at Amazon right now if you pre-order. You might have to check the right side of the screen to see if it's from Amazon (I know they have a third party seller listed for ME2).
http://www.cheapassgamer.com/forums/showthread.php?t=284487