I REALLY want braces!?

I need to convince my parents to get me braces. I only have one tooth crooked but its right in the front. I am really self-concious about it. Laughing and smiling are hard because I feel like i have to keep my mouth closed. twice people have even said something about it. One day i was at a restaurant and one of my friends ped around a phone with this hideous lady as his background with crooked teeth to show my other friend his phone and my other friend shouted "Hey! It looks like Lindsey!" It was really embarssing. Eveytime i try to talk to my parents about it they say its too expensive or there working on it. I REALLY wantt them, please help