How to finally save up?

For about a year I have been trying to save up to buy this electrical moped to ride on around. I'm 14 and a girl. Every time I begin to save up a large amount of money, I end up buying something then regretting it within the next few days. I have alot of change saved up like $40-50 which my parents are holding onto. Also, I have $80 but that added up isnt even half the amount. How do I save up?