Originally Posted by ikbenrichard 
Weird that people pay such an amount for a guide for a game not that complex.
A lot of people (for example, like ME) buy guides for their favorite games as collector pieces and references for subsequent play-throughs to find experiences that may have been missed during an initial play-through.
It's a lot of fun to have a guide years after the release of a game - for the most part, the guides will contain everything you'd ever want to know about the game all in one place.