First of all, from your height you're not that far overweight -- it's not like you're a hundred pounds overweight. To properly drop the 30 pounds you probably need to lose you need to do it slowly. Cheap food isn't necessarily bad food or fattening food; there are also programs for people through charities, the gov't and religious groups to help get you to sources of healthier food. I don't know if your parents are willing to do this, but if you are, the first thing you might do is see if there's a food coop anywhere you can get to where you can volunteer. Or you can try getting a job at a grocery or health food store. Two reasons for this: you get a discount for doing this, and these places throw out or donate a lot of good healthy food and employees usually get first dibs. You might have to work to find your solution, but it's out there and you're young and strong so you can do these things.
First of all, don't stress about the situation your in now. That's how most people gain weight, by stressing out. You shouldn't worry about what brand of food you eat when you try to loose weight. When I lost 30lbs I just ate healthier, balanced meals. Lay off chips and soft drinks, and candy. Those are things that don't benefit you. Also, excerxise more often. Many people think that's loosing weight can happen if you just eat right, but that is not the case. You also need to eat to lose weight, you can't just eat a little food then only excersise. The most important thing is to stay positive, and if you work for it, it will happen.