I would not do it that way if I was going to do contracts. Unless you are getting the money up front why give them a discount? That is just taking money right out of your pocket for no reason.
I'm assuming the numbers you are using are just for example, if not thats another concern of mine.
I don't see how a contract benefits you and in your above scenario it actually hurts you quite a bit.
Where are you planning on going to college? Will you be nearby? What is your current workload and how many years until school? Do you have any helpers or partners or is it just you?