I actually have found eating healthy is cheaper than buying all the processed stuff most people buy. Maybe you can't afford organic stuff, but there are places where you can byt cheap. I get great deals on fresh produce at several places and buy meats and other things only on sale. In fact, most things I buy only on sale. Some can be purchased in bulk, like rice, beans, canned corn and the such.
Further all those processed things are LOADED with salt and sodium based preservatives. And I drink mostly water as everything is loaded with sugar. Complex carbs such as spaghetti is not so expensive and can easily be obtained on sale and you can get canned tomaotes and stuff on the cheap too. Even yougurt can be gotten on sale and when there is none, I buy the big nonfact plain and flavor it with my own fruits. In the summertime you can grow things too. I think you could be pleasntly surprised shopping for the good stuff.