probly on wwe.com during halloween time or at halloween store.
You Can Buy A Halo Kid's Costume On http:/www.Amason.com
you can buy one at Party City
any
You can buy children's halo costumes from Party City. They can also be purchased from Amazon and Costume SuperCenter.
No one specifically makes them for kids but if you look at amazon or ebay or ext. you could find some that are tailored
Police officer costumes for adults and kids are very popular and it makes them easier to find. Check out these websites for a variety: http://www.buy-cheaphalloweencostumes.com/police-costume-for-kids/ and http://policemancostumes.com/kids-policeman-costumes.php.
You can find plus sized costumes quickly and at reasonable prices at www.buycostumes.com. The site should have all your costume needs for both you and your kids.
you can at walmart.
You can buy it at Playasia.com
www.walmart.com has a cute kids cupcake costume. You would have to wear a unitard under it, as pictured. There are also directions for making one yourself at www.squidoo.com. It looks pretty straightforward.
Costume shop
There are plenty of Riddle Costume for all ages that you can buy at many halloween costume stores.