Don't do it, benson. Going to a formal will destroy you. You'l be there surrounded by dozens of other people, in a noisy, busy environment. That's no good for building a relationship with a girl. Don't you think going somewhere with just the two of you would be better?
Meeting up and playing Pokemon together, or getting a private booth at McDonald's, or something like that where the two of you get to spend some quality time together. That trumps anything you could possibly get out of a get-together you have to pay to attend. Take my word for it.