The growing trend is that it is more expensive to eat healthy then to eat junk food. I believed this for a while, but I have lived in a house that eats only fast food and prepared items that go from freezer to oven to plate, and now in a house that eats healthier foods, and my grocery bill has definietly gone down.
A few things I have discovered is that fruit is an affordable and easy option for snack time. I purchase a bag of apples every week, for about $4-$6. While this may seem like a lot when a bag of chips is only $3, but that bag of chips will last about 3 snacks and the bag of apple comes with 10 or 12 on average, though I regularily get 14 or so. This can be an apple for a snack, or they can add change and flavor to meals. I use apples on top of pancakes, and pancake mix is very inexpensive and lasts for several servings. I also use apples for desserts, along with other fruits, and they also travel well. No wrappers, no packaging, you don't need containers or bags.
Another great option is a bag of potatoes. I can regularily get a 5 or 10 lb bag for $3 (depending on the sale) and I use them for so many things. Suppers, potato pancakes for breakfasts, and I use them to make my own chips for much less then purchasing a bag of chips. Potatoes are high in vitamins and one of the healthiest foods (I watched a Body Break commercial!) and are very versatile.
Through tracking my shopping and keeping receipts I've found several healthy options for snacking that are more affordable then prepackaged options. Raisins, bananas, apples, carrots... all are affordable, and so simple to grab and eat with no preparation. I save even more by growing vegetables (I had an indoor garden when I didn't have an outside one) Vegetables can also be added to other foods to make them healthier and more filling. One banana can be as filling as a quarter of a bag of chips, an apple is more filling then cookies. I find that while the healthy foods may appear to cost more to start with, they make you feel fuller faster, and the feeling lasts longer.
When I have a very limited budget (and I have, I promise you, had a very tight budget several times) my main purchases are always potatoes, apples, rice, and beans (canned or the bags you need to cook yourself) Replacing meats is more difficult, and meat is by far the most expensive staple. I know there are a lot of replacements for meat (many can be found online) but in my house we use potatoes, beans, lentils, etc most. Rice can be a great filler, though there isn't a whole lot of nutritional value to it. When purchasing meat I try to save where I can. Chicken breast is expensive, but one chicken breast will feed both me and my daughter, whereas it would take 12-14 chicken nuggets to do the same, bringing the cost more even then first impressions would imply. My favorite way to get chiken is to purchase the whole fryer chickens on sale. This cooks well in the oven and the leftovers are great for sandwiches, or can be used to create a soup or even into a stew. Breakfast sausages, while not the healthiest meat, is in my opinion better then none for a day or so a week, better then hot dogs at least. They are more versatile then you'd think, I use them instead of hot dogs to go into KD and it goes well into rice for a quick and easy meal.
You may not agree with me, and prices may vary by location, so this may not apply for everyone, but in my house, it is definitely proving a little cheaper to eat healthy. I also