The collectors edition contains both the strategy guide (normally £12.99) AND the art of Mass effect (normally £17.99). i've just been into my Hull branch of Game and this was £9.98!! I'm sure it doesn't take a genius to work out thats almost a third of the price. Game normally sell these for £17.99 for the pair so it's still a pretty good deal!
One for the collectors if you're into the 'art of' video games. Offer ends this week when GAME sale ends.
This doesn't seem to be an online deal, but I've included a link so you can take a peek.