Taken from the most delicious game blog in existance.

    Although they won't be able to help you get your money back for the far too small and easily available legendary edition helmet, Urban Collector is now offering pre-orders for a deluxe full-size Master Chief helmet. Judging from the one picture provided the helmet looks pretty well done. However the helmet only comes in one size which is listed as "adult." The helmet is currently available for pre-order at $89.99 and will ship August 08.

Urban Collector is also offering a deluxe costume/helmet combo available at the pre-order price of $699.99. This at first may seem expensive, but think of it as an investment. Just wear the costume all the time. This may lead to a legal name change, which I personally wouldn't do but highly endorse you to do so. The costume/helmet combo also ships August 08.

Lesser quality Master Chief costumes also available here.

Source via Evil Avatar