Was thinking the same thing you are when I bought mine back in 06. It was my only car and I needed the gas mileage to be bearable. If you DD the car, save your cash, when you get the money, time and/or another vehicle, get a blower or do a full PI swap with cams and LT headers. If mpg is a necessity, I wouldn't recommend doing anything extensive. HCI or blowers will negatively effect your gas mileage substantially.
For the time being do things that won't absolutely kill your gas mileage. Maybe 3.73 gears and an offroad pipe.