I always check toysrus.com because they show some master chief {Halo 3 editon} costumes but i can't say that those things are cheap.
yes
yes
You can buy children's halo costumes from Party City. They can also be purchased from Amazon and Costume SuperCenter.
You can probably go to a costumes store or order them online.
Rubie makes a wide variety of costumes for both kids and adults. Kids costumes include Spongebob Squarepants, Speed Racer, Veterinarian, Mermaid and Frankenstein among many others. Adult costumes include characters from the Wizard of Oz, Lady Zorro, Halo 3 Master Chief, and Wonder Woman among many others.
Of course there is. Google is your friend.
You can get them on eBay but they are dear about $50
game traders lol:)
You can purchase a variety of green dog costumes from http://www.buycostumes.com/. There are many green dog costumes that you can pick for children or kids.
I don't think there is a kids Halo Spartan costume out yet.
There are many different places to purchase costumes for kids such as the Disney Store and also on there website. Around Halloween places like Walmart, Costco or your local costume shop will have lots of costumes for sale.
party city