This costume is quick and easy if you already have the materials. However, you could probably make some substitutions.
Corset- Mine is a gold, flat-topped variety.
Underdress- should be strapless, floaty, and princessy. I used this one
(the dress I wore to senior breakfast forever ago).
Overdress- caution! This dress will never be the same again! I started with this one
, from Dharma Trading Co.
Extra hair! I used Afrelle Kanekalon. It comes in a braid. See this page.
Get at least three of these. I used five, I think? Maybe six?