I'm going to have to agree with the people saying things like spag bol, stir fry, curry etc - and stuff like macaroni cheese (although I suppose that comes under 'pasta'!) is good as well.
I would say, however, that the meal option I go for most often at the caf at uni is the 'Select-a-sandwich' thing. You can choose your type of bread (white, wholemeal or grain, even rolls, turkish bread and paninis)and then choose a meat (chicken / smoked salmon / beef / bacon /roast pork) and 3 'veg' (carrot / tomato / gherkin / cucmber / alfalfa / lettuce / avocado /cheese etc etc the list goes on) and then as many sauces as you like (everything from pesto to hummus to roast garlic aoli). Then if you want you can have it toasted. *drools*
I realise this sounds kinda like subway, but the point is that a) people love subway, and b)the sandwich will only cost you like NZ$8, and that's if you want extra fillings and the pricier bread..I get a huge, awesome sandwich, crammed with fresh, tasty and healthy fillings, for NZ$4.50. Which if XE.com is correct, is like US$2.80.
I don't know if that's cheap by your caf's standards, but man, does it taste good... =)