I was at my local game stop yesterday and I was informed that they were taking reserves for Halo 3, and that there would be not 1, not 2, but 3 editions of the game, the standard release, limited edition and a $100 legendary edition with a spartan helmet and tons of other stuff. I was told that they were only doing limited reserves on this and would stop after this weekend.
BTY it is $25 to reserve the legendary edition.
EDIT: Game Stop has called everyone (March 16, 2007) and informed that the new suggested retail price for the Halo 3 Legendary edition will be priced at a whopping $129.99!