This is the very limited and special Halo 3 edition of the Xbox 360 console (Equivalent to the new Pro version) but is designed for the person that likes to be different, Halo fans or for people that love collectables, as no doubt, this will be worth money in the future, especially when you consider hardly any retailers are selling this.
The Halo 3 console is exactly the same as the standard Pro version but has a special Halo 3 edition casing on the console with an exclusive look on the wireless controller, hard drive, Headset and will come bundled with exclusive Halo downloadable content and will come bundled with a a Play and Charge Kit (can be found for around £12) which is essential for recharging your wireless controller during gameplay.
I've checked on search engines and there only seems to be only 4 online retailers that are selling this special limited edition console and they are all charge the full retail price of £279.99 (including Play.com, HMV & Amazon) apart from Tesco who charge £267.63.
I also saw the deal listed on here a couple weeks ago for £279.99 from Amazon but it came with a free halo 3 game and was a very hot deal but you could buy the game for £29.99 from Shopto anyway, so that means the package still works out £30 less.
The console isn't instock right now but is expected to be instock within the next couple days according to there forums.
Hope that helps. :)
Xbox 360 Special Edition Premium Halo 3 Console
Xbox 360 Special Edition Halo 3 Wireless Controller
Xbox 360 Special Edition Halo 3 20GB Hard Drive
Xbox 360 Special Edition Halo 3 Wired Headset
Xbox 360 Special Edition Halo 3 Gamer Pics and Theme (Exclusive download via Xbox LIVE)
Component HD AV Cable
Play & Charge Kit
Xbox LIVE Silver Membership
One-month Xbox LIVE Gold Membership