No idea how long this deal will be going on, but pre-ordering H4 direct from the micro$oft store will grant you a 25 Dollar coupon off of a future purchase from the mircosoft store.
Pretty decent deal, but I cannot find on for the limited edition, So if you're waiting to pre-order, I would wait to see what Amazon and newegg get for first week deals here in a few months.

Offer in question:
http://www.microsoftstore.com/store/...l/pbPage.Halo4