Microsoft laid down their plans for pricing earlier at a game convention in in Germany:
There will be 2 models for purchase, one will be the "economic" version ($299) and the Other regular Model ($399) will contain extra contents not found in it's counterpart.

$299 version
-1 wired controller
-1 faceplate
-XBL silver membership
-AV cables

$399 version
-20GB detachable HDD
-1 wireless controller
-1 wireless XBL headset
-Hi-Def AV cables
-1 Ethernet cable
-1 Remote (DVDs etc...)
-1 faceplate
-XBL silver mambership

Thats quite heavy..........and expensive

Hey i just wanna know whos gettin PS3 MGS 4 and DMC 4 cause i know im pre-ordering them all :D