The Halo 4 soundtrack is available in October; available in acceptable or pricey options
Now, don't get me wrong here: I love video game soundtracks. Hell, I own all of the Halo soundtracks to date. But, I don't think an option that costs more than the game it's for is a very smart idea.
Maybe you disagree. If so, the more expensive of the Halo 4 soundtrack options will set you back $75 US, and contains the standard soundtrack, a 14-track remix album, a 12-inch art print signed by composed Neil Davidge, a vinyl copy of the soundtrack, a special Xbox Avatar shirt, a behind-the-scenes "Making of Halo 4 Music" DVD and hardcover book with "composition notes from Neil Davidge plus exclusive behind-the-scenes photos and exclusive artwork images."
If you're looking for a more economical bundle, the standard edition Halo 4 soundtrack is available in both physical and digital formats for $14 US.
Once you've committed to either soundtrack version, you can go and order it at the Halo Waypoint.