Where can I find a mardi gras costume that is appropriate for my daughter?

This site is probably a good first stop: http://www.mardigrascostumes.com/ but there are many others which are equally sensible; http://www.costumecraze.com/Mardi-Gras.html and http://www.buycostumes.com/browse/Adult-Costumes/Mardi-Gras/_/N-3iZ27/results1.aspx are two.