Amazon has the uber Halo 3 Legendary Edition available for pre-order!  Pay no tax (in most states) and get free shipping with your order!  Also, Amazon does not charge you until the item ships.

Important News Regarding Pre-orders: Due to extremely high demand for and limited availability industry-wide of the Halo 3 Legendary Edition, Amazon.com will be taking limited numbers of pre-orders and will limit these to one copy per order. We will notify all those who signed up for an e-mail when we begin to take pre-orders, so keep an eye on your e-mail box and good luck!.

Check it out:  Amazon - Halo 3 Legendary Edition