I've been doing all my research for this costume too.
Most commonly, people make this out of spandex. Somewhere like spandexworld.com. Most spandex/lycra is around 6 Oz/Sq Yard, but I think she needs a little more structure for her suit and you're better off going for an 8 Oz/Sq Yard.
As far as patterns go, there are none. From the couple of creations I've read, they've made a leotard from a stock pattern and deconstructed the front to create the shape.