My college diet staples revolve around several things in mass quantities, focusing entirely on bang for the buck. Money is often very tight, and with entertainment and social expenses, some creativity is needed.
The first and biggest is ramen noodles. I prefer the Maruchan brand in terms of price vs. quality; when the local grocery store has sales on Maruchan ramen dropping their price to ten or sometimes twelve packages for a dollar, I buy nearly disturbing quantities of the stuff. Varying the flavors helps a lot, as does adding a lot of pepper, which is also cheap. I particularly recommend the Maruchan chili, roast beef, roast chicken, and chicken curry flavors.
The "whatever is on sale" category is also a major college diet staple for me. The circular for the local grocery store is almost like a holy document; I carefully examine the items on sale for the week and calculate what I can purchase to maximize quality and quantity for the buck. Of particular interest are items that are already very inexpensive; when the usually two for a dollar Patio medium frozen burrito is on sale at three or even four for a dollar, I stock up.
Generic unsalted crackers are also very cheap and provide a lot of food for the cent. Several crackers along with a package of ramen noodles provides a very inexpensive meal (roughly ten cents).
Rice with sauce made out of flour, water, and random spices (curry is excellent if you can get it cheap) is another staple. Every time you visit a fast food restaurant, scavenge their free sauce selections for some additional rice toppings.
Bread, peanut butter, and jelly provide the ingredients for several cheap sandwiches per loaf of bread, and one can go through several bread loaves before running out of peanut butter or jelly. A sweet and cheap alternative choice.
Requesting a pizza oven as a holiday gift was a brilliant idea for me. Now, I am able to buy the cheapest pizzas that the store sells (usually Jack's at six for ten dollars, or roughly one dollar and sixty six cents apiece) and make them quite delicious by adding chile peppers and regular pepper and mastering the controls of the pizza oven. The pizza oven cooks the pizza perfectly and a frozen pizza well cooked is quite tasty. Considering I can stretch the pizza to three or even four meals or so, it is economical as well.
Fresh fruit and vegetables are often surprisingly inexpensive and also healthy. I choose those which are very easy to prepare, such as seedless grapes, baby carrots, bananas, and so forth. This is usually a breakfast staple.
Kool-Aid by the packet is also a godsend. Much cheaper than pop (or soda, let's not have soda or pop? here), it can be augmented with a reasonable amount of sugar, which itself can be scavenged from the restaurants that I visit via collection of sugar packets. Tea in large quantities is also good and very inexpensive for a warm evening beverage.
The staples of my college student diet focus on inexpensiveness, bang for the buck, and at least minimal nutrition.