That isn't a completely unique idea. At my school, we are paid $100 for each AP test we pass in English, Math, or Science. This money is coming through a partnership with TI. This is fairly effective in giving students both a reason to take the test, as well as a reason to spend extra time studying. I have heard of several other schools that are also doing something similar.

This works very well in generating interest for the tests. However, it might be a bit harder working a system like that for other grades, because you need to find a uniform scale to compare everyone to so you can determine how much money they will receive. But if a grant can be made, it would be effective in making people care about their grades, because most students care much more about money than something as intangible as academic grades.

Because of this system and the effort I had to put into studying, I certainly know that I am going to be enjoying spending the $300 that I earned.