I used to do an egg and a couple pieces of lunch meat.

Now I don't eat eggs or meat anymore, so I tear up a sheet of nori (dried seaweed), add about six ounces of cubed tofu, one spoonful of sambal oelek (chili paste), and a little bit of sesame oil (add the sesame oil last, after taking it off the heat).

Per serving, the tofu is the most expensive, then the nori, so if the budget is tight you could cut there (but the tofu is also the only protein). One container of chili paste or sesame oil is enough for many servings, I couldn't say how much it costs per serving but it it's probably less than the noodle packet.