It finally happened yesterday...DD2 ran out out of money. She is our little spender. It is so hard for me to let her spend money on things that are "whim" purchases. But I kept telling myself, "This is her money, not mine," and "different people value different things, my kids included."
Also, she needs to feel the pain of running out of money if she is going to learn how to save. And boy did she feel it today. DD1 went clothes shopping (at Justice with a 40% coupon), DD2 LOVES Justice clothes and was so sad she couldn't by anything. But it was SO good for DD2 to feel that.
After the experience, DD2 is really resolved to be a better saver. It opened up some great conversations about past purchases, putting off spending to see if it is a want or a need, and saving for what you really value. (I could even politely say, "I told you so". :)