Ramen noodles are a good thing to buy to have around...but I don't use the seasoning with them when I cook, just get some spaghetti sauce and some other seasonings to mix up the flavor and save your heart from the ungodly amounts of salt in those things if you prepare them properly.
Frozen burritos are also a quick fix to have around, unhealthy, but good in a bind.
Here are the things I usually buy though (the bare essentials anyways):
Hamburger patties....they're premade so you know how much you're eating (can help with dieting and such), very versatile. You can make a burger, or defrost them for a bit and use the beef in anything. At Sam's, it's $14 for 40 patties, not bad.
Rice...you can do amazing things with rice. Curry rice, plain rice, rice and butter, rice in a tortilla with your beef, rice with fried vegetables, rice with meat on the top, really just about anything, and it's $5 for 20 pounds.
Seasonings, lots and lots of seasonings....Food does not taste good without them, plus, you can make a single entree into 50+ if you have the proper seasoning power. I use garlic, seasoned salt, curry, pepper, red peppers, oragano, marjoram, cinnamon, cajun mix, and bay leaves more than anything else, but don't limit yourself to anything.
Beans...any kind of beans, again, nearly as versatile as rice, but they provide protein which is a good thing, then you don't have to consume the calories and fat in meat all the time.
That's just a start, but rice, beans, and meat are essentials IMHO, then just learn how to cook a bit. Look up some recpies online and experiment...not too hard to fingure out some things you like.
