re: kids spending money

I don't have an exact dollar amount, but one of the most interesting things I've seen done was to give the child a monthly lump sum for all things outside of normal food, shelter, and clothes. The dollar amount was determined using a factor off of his GPA. The higher his GPA the higher the amount of monthly money he was given.
For example, the child had a 3.0 the previous semester so he was given $300(estimate) a month to cover anything he wanted outside of the home and normal routine. So everything outside of school uniforms, food at home, etc was spent with "his" money at his discretion. Things like football cleats, basketball shoes, movie tickets, eating dinner out with friends, homecoming clothes, concert tickets, etc were all on his dollar. He could get his monthly pay and go buy a truckload of candy if he wanted but he would be without new shoes for basketball season. I remember the kid never went without and always had nice things, but it was up to him to prioritize where his money went.

It apparently worked well for him, because he has a Lamborghini now.