Ramblings from another nerd on the grid
Looking for an official Bungie Halo 3 licensed costume? Well, the Rubies officially licensed costume is finally out. Check out the detail on the costume. Get the costume at http://www.odysseycostumes.com/master-chief.html. High resolution image of the costume there. Have fun smacking the Covenant with your battle rifle.
After spending the $700+ on the costume you must then build a full-scale, replica battle rifle from LEGOs: http://www.mocpages.com/moc.php/9348
Only then will you be ready to "Finish the Fight!"