You could also probably save your creatine on your training days. There is 1g of creatine in the C4. If you feel that the 1g is not enough you could lower your dosage of the other creatine at least, help it span out longer for sure. I have personally never seen a difference in taking 2g of creatine versus 5g. Then again, I do eat a ton of red meat.
For carbs you cannot lose with rice, oats, and potatoes. That stuff is very affordable.
For protein, eggs, ground beef, tuna in a can, whatever meat that is on sale, chicken, etcetera.
Buy some veggies with it and you're golden man.
You can make burritos at home for pretty cheap. As well as stir fry and jambalaya type dishes.
Some people might baulk at this, but for awhile I went to Wendy's and would get three Jr. Cheeseburgers directly after my workout. This costed $3.17 and provided 840 calories, 45g of protein, 39 g of fat, and 75 g of carbs.