Individual Reward System

One of the student's I tutor has a hard time staying motivated when we work on reading comprehension and phonics.  A reward system motivates him to try his best and stay focused. The systems I have been using have cost me a lot of money because I would have to continue to buy rewards too often. I am implementing a new variable reward system using a deck of cards. Here is how it will work:

1) Whenever I want to positively reinforce student behavior or something the student does well (correctly answering a question, using a strategy we have discussed, etc) he will get to flip a card over from the deck.
2)  If the card he flips over is hearts then he get's additional reinforced by adding a check to a table I have created for him.
3)  If the card isn't in the hearts suit then we continue to work and he isn't additionally reinforced.
4) On a sheet of paper I have a table with 10 boxes per row.  For every row he gets fully checked I will bring in a prize.

At the beginning, I will make reinforcement easier so he understands the concept. I will do this by allowing him to check a box anytime he turns over a black card.  After a few days of this, I will change to reinforcing him for only the hearts suit. I really like that this system will allow me to fade rewards by changing what card reinforces him.