Here is a good general rule. If its processed and easy to make, its probably terribly bad for you.
You can never go wrong with lean protein and some greens. You can buy a huge pack of chicken thighs if boneless chicken breasts are too expensive for you. A head of lettuce, tomatos, cucumbers and onions are cheap. A little salad dressing of your choice. Bake the chicken, add some spices to it, cut up the salad mix and voila, you have a easy to make meal for pretty cheap thats really good for you.
Stay away as much as possible from stuff like hamburger helper, ramen, mac and cheese, etc. Although they may taste good, and are easy to make, they are terrible for your body.