I realize that I am a little late to this conversation, but depending upon the problem you are trying to correct, you may be able to get by developing corrective habits. I went to school with a girl whose family couldn't afford to fix her protruding overbite (think bad buck teeth). Her family was told by a kind dentist to have her play the flute, as the constant pressure of her lips pulled across her mouth would make her teeth move back in her mouth--but only if she really practiced. She has a lovely smile, and as an extra benefit, she paid for college with her band scholarships.