> Food that is good for you is just more expensive than food that is bad for you.

It's not a relevant difference. Sugar and rice are the absolutely cheapest calories, and they're not so good for you. But a can of coconut milk is ~700 healthy and tasty calories for about a buck. Eggs are healthy and pennies a pop; you can even buy them already hard boiled. A can of sardines is a couple bucks. A can of sauerkraut is a buck and loaded with nutrition.

You have to be a moron to fail to put together a decent day's worth of food at a grocery store given $8. If you're willing to eat high starch you can eat for a couple bucks a day.