Get Halo 4 for $44.99 at Newegg by using coupon code "EMCYTZT2339" during checkout. This coupon is good through 11:59 p.m. PST on Sunday, October 14.
Unfortunately, the Halo 4 Limited Edition is sold out pretty much everywhere including Newegg so the discount can not be used with it.
Free shipping is offered but delivery should be expected three to five days after the release date with Newegg. It could reach seven days depending on how far out you live. Tax is not applicable in most states.
If the $15 discount at Newegg does not interest you, you may want to check out the Microsoft Store which is offering a $25 gift card with the purchase of Halo 4.
Halo 4 is set four years after the end of Halo 3 which saw Master Chief and Cortana stranded on the derelict UNSC Forward Unto Dawn. They've somehow drifted to the mysterious Forerunner shield world of Requiem but an offshoot of the Covenant is there too looking for ancient weapons to wipe out the humans with.
The Xbox 360 exclusive is set for a November 6 release date.