Do you have a Sams Club in your area? I eat a diet very high in veggies and fruits, and buying many of them at Sams helps.
Romaine hearts are just $3.98 for a pack of 6. They are large, about 8 ounces each, so each one makes a huge salad. I go through 2 bags per week.
Organic baby spinach is $3.98 for a large one pound container. I eat a few per week, using them in salads, smoothies, or cooked and seasoned.
I also buy bags of sweet mini peppers, cucumbers, zucchini, and other veggies there. They sell a wide variety of fresh and frozen vegetables.
I buy frozen blueberries at sams for about 6.50 per 3 pound bag. I eat a cup or two daily, or one bag per week.
Lentils are another good budget food. You can eat a serving for just pennies, if you buy them in the bulk section of a local natural foods market. They are packed with protein and fiber, and they are very versatile. I usually add some to my green salads. I keep packets of precooked and measured lentils in my freezer.