Personally, I feel there is a severe flaw in the argument that healthy foods are "too expensive". The thing people seem to forget is even if the healthy foods are a little more expensive than the junk foods, your body will crave a significantly higher volume of the junk foods to feel "full" than the healthy foods due to how nutrient scarce they are - which means you actually end up buying more junk food to stay "filled", spending more than one would with the more "expensive" health foods.
Think about it. How many people will sit down and eat a bunch of banana in one sitting? Compare that to a bag of potato chips? So people will buy 5 bags of potato chips at $1/bag because it's "cheaper" than buying a $1.50 bunch of banana. So one spends $5 on potato chips for lunch vs $1.50 for 7 bananas (one for each day).
When I switched from eating boxed/processed foods to eating live foods, my grocery bill actually went down. I used to spend an average of $40-50 per week with processed foods, and now I'm spending about $35 per week buying mostly fresh fruits/vegetables/meats.
The other thing, there are several vegetables that can be grown inside. I just learned how if you buy a celery stalk, you can cut off the base, place the base in water, and the center will start to sprout new celery. Transplant it to a pot, and in about 5 months, you'll have a mature plant to eat as needed, and it'll keep growing. Start a plant like that every month, then you'll never have to buy celery again. Same can be done for growing carrots, garlic, onions and lettuce - and many more. Investing in this is more than worth the return in fresh produce.
There are many ways to keep grocery bills down and eat healthy. One just has to decide to make the change and stick with it to see how you really do end up saving money by eating healthier.
Another benefit - think of all the medical bills one will not have by eating healthier. You eat healthy, drink water, exercise - you don't get sick as much = savings on medical bills. Don't forget to calculate that into the "cost" of eating healthier foods. I'd rather spend an extra $10 a week for healthy foods compared with $100 in medical bills per month due to complications from unhealthy living...