When I was younger and knew almost nothing about cooking (I once called my mother to ask how to boil potatoes), my friend Robin recommended that I get a copy of The Joy of Cooking. As others have noted, it's a book that comes in handy from time to time (like when you are asking yourself "what the hell do I do with this rutabaga?"), but for the most part, it wasn't for me.
In recent years, I realized why: I am not interested in cooking. I am only interested in preparing food to eat. Those of us who want to prepare food to eat because it is healthier and thriftier than buying prepared food are a different breed from those who want to know how to make puff pastries with a bechamel sauce and the like. We want to know simple things like, how do you prepare vegetables good enough to eat without spending much time on them? What can be done with a frozen chicken breast? Is it worth making pasta sauce from scratch? What are canned beans good for?
So in anything I write here about cooking, please keep that basic outlook in mind. Nothing I suggest will result in a food that will amaze and delight your friends - it's just not that kind of cooking. For one thing, it's very difficult to amaze and delight anyone with food that's healthy and cheap (if by "healthy" you mean, as I do, "healthy according to current medical research," and not something like, "healthy because this is wild Alaskan salmon and organic butter").
But if you are, like me, interested in preparing food to eat, and you like that food to be both healthy and on the cheap side, and preferably simple to prepare, I might have an occasional useful tip.