Instead of paying a student for their good grades, help them raise money for your group by getting a good report card. Find sponsors who will pay a certain amount for every A or B on their report card. Maybe have a bonus for an all A report card. This will be great motivation for students to study hard and keep their grades up. Work with the teachers and see if they will keep a running total so each student knows where they stand. Provide tutors to help those students who need it. Allow each student to photocopy their report card to send it to their sponsors along with envelopes so they can collect the money. Have each student send a thank you note to each sponsor letting them know what your group will use the money for. Throw a pizza party at the end of the fundraiser for all the students to thank them for all their hard work.