This will have a lot of links.
First, philosophy and technique-- which is not what you asked about, but has been discussed in this context a couple of times.
A simple handy stir fry that isn't complex.
What does healthy and cheap mean to you? For most of the world, and in all the famously healthy cuisines, it means a whole grain and a legume (beans, peas lentils). Those two combined create a complete protein, plenty of fiber, and lots of related nutrients. But it also means longer cooking times as they take a long time cook to completion from their inexpensive dry state. This isn't necessarily a problem for a college student as this is mostly time simmering in pot while you can study at the kitchen table.
I like Michael Pollan's words:
Eat food, not too much, mostly plants.
The other thing the rest of the world has learned that the US hasn't is to use meat as a flavoring, not the focus. Much more healthy, less expensive too, and usually faster to cook.
As my daughter is discovering in her first year at college, cooking takes time. Figure 30 minutes minimum plus clean up. There are some recipes that are faster certainly, but figure on some time. For this reason, it is good to make some extra and eat leftovers on crunch times. Freezing some leftovers is good too.
Whole chicken and eggs are probably your least expensive protein sizes/amounts that are reasonable cooking for one. learn how to disassemble a whole chicken. It doesn't take long and you can make chicken stock for very low cost that opens up a lot of other good food.
Chicken cooked on the bone and skin on has much more flavor than boneless skinless. Boneless skinless thighs are much cheaper than boneless skinless breast. But buying a whole chicken is the cheapest by far.
If you want boneless chicken, this technique is the easiest.
A handy method for using up leftovers, particularly pasta is a fritatta.
In the recipes section, start a new thread on College recipes or some such, and i'll give you some more of what I've shared with my daughter.
A final tip.
When you come home, the first thing you do is put some water on to boil. Beefore dropping off your coat, or books, start the water. This way while you're putting stuff away from the day, when you get to the kitchen, your water is ready for pasta, or rice or vegetables or whatever.