My daughter was also valedictorian, and no, we didn't pay her for getting high grades. I don't understand the philosophy behind it - no two classes are the same, some classes/teachers are much easier to get an A in. What do you do if one child struggles in school, tries hard, and gets all C's and B's, the other kid has it easy, is lazy, and gets mostly B's, and a few A's?
I expect my children to do their best at school, and don't need to bribe them to do so. Working hard, challenging themselves, and wanting to do well for themselves, not the $$$, is what makes them successful.