^Try www.intencity.in. You will get it for cheaper than retail stores. Then again, you do have Ebay. Eitjer way, it is very cheap as well, just 699 bucks!
Also, buy the Game of the Year Edition.
On May 11, 2010, a Game of the Year version of Batman: Arkham Asylum was released in the United States. This edition includes four new challenge maps and is packaged with two pairs of glasses which may be used to play the game in 3D using an anaglyph image technique viewable on any television.