@SupaPhly part of the reason could be that they are more responsive to FOREX fluctuations than MS or Valve. The other reason is that we are so small for Sony that they can't be bothered to match what happens on the other platforms.
If you have both consoles it allows you to price shop, i've picked up a few games this way.
The Legend of Korra: The Art of the Animated Series - Book One: Air (HC)
This handsome hardcover contains hundreds of pieces of never-before-seen artwork created during the development of Season 1 of The Legend of Korra. With captions from Mike and Bryan throughout, this is an intimate look inside the creative process that brought the mystical world of bending and a new generation of heroes to life!