Dell Home has Xbox 360 Elite 120GB system bundle including Forza Motorsport 2 and Marvel Ultimate Alliance games for $300 Xbox Deal on Dell website from http://slickdeals.net/
Seems like a price mistake. Deal is back to $450, and it seems like some people got confirmation emails with the price being $450 (excluding tax, shipping, etc.). Maybe they'll honor some of the orders that got placed (and confirmed) before they noticed the mistake though.