I'd recommend a light or medium weight twill. You can find them in joann's in a variety of colors (as I recall, generally found in the "bottomweights" section), though I'm not sure if they usually have purple. Quilters cotton comes in all kinds of colors, but I think it would be too flimsy for something like this.
For the sleeves and leggings, go for a knit fabric of some kind. If you can't color match the two, get white and dye it. It's a lot easier than it sounds, honest!