>>1439349>>1439350Latex comes in all sorts of colors, but black is generally the most common. I have seen brown latex before, though.
I'm not too sure of the exact costs, but it certainly is expensive. Latex is one of those things where you definitely get what you pay for, as lower quality latex can tear easier and such. A decent-quality catsuit would run you at least $200.
What were you planning on cosplaying, BTW?