I'm going to my county's Comic Con this August, and I want to cosplay, but I don't know who to cosplay as. I want to cosplay as some superhero, probably, but I don't want to spend a whole lot of money to do it. Any suggestions? 

Oh, further note, I only want to cosplay as a girl because I am one, and I have brown hair that I can't dye again because I'm allergic.