Not only would this motivate students to try their hardest to get a good grade in order to gain the money, but they will also be able to help their parents pay for bills. Some middle school students in the Washington D.C.'s Capital Gains have already started to save up for college.
It takes a great deal of hard work and discipline to achieve good grades. Students who do this should be rewarded with monetary awards in the form of scholarships so that they can continue their education should they so choose. Monetary awards in the form of cash for good grades, however, are a different story and should never be awarded by a school.
There should be no grades at all. Students should be motivated by their desire to learn and internal, not external, motivation. That said, as long as adults tell students that it is their job to go to school and earn good grades that are meaningless to the children themselves, they should receive some sort of compensation.
Children should not work towards academic achievements with only monetary awards as their goal. They should understand that society does not owe them anything. Rather, they have to prove useful to society in order for the community to reward them - monetarily or otherwise. Children must understand that good grades are personal achievements and that working toward them is something that they do for themselves, not for others.
No, students should not receive monetary awards for good grades because they need to learn that success is its own reward. Life does not always provide money or other rewards for a successful attempt. Students must learn to achieve success simply because they want to do a good job, not because they expect payment.