Whoah, whoah! Sorry if this sounds a little preachy or nasty, but...well, I think you're being a bit whiny about this. Sure, it's your money, but you can still have fun with what you have. Winning doesn't really matter. You can always dye it, anyway. Just because your parents won't let you buy a wig doesn't mean you should throw a tantrum and take your anger out on them. Remember, they paid for you to get to the convention, they're the ones who are letting you go, they're paying for the hotel, and it sounds like they're paying good money to help you buy this costume. Maybe when you're a little older, you'll figure out that you can't always get what you want, and sometimes you just have to take what your parents give you. It's disappoiting, but you'll get over it.
Let me tell you, I'm old enough to drive, but I'd be damn happy if my parents were nice enough to send me to Eirtakon out of their own money.
To the mods: Sorry for posting back-and-forth like this...just wanted to say this.