Oatmeal can be gussied up fancy or eaten plain. It can be eaten hot or cold or made in a large batch and parceled out over many, many days.
I like mine with raisins and dried cherries. Yeah, I know...I am soft because I wallow in luxury.
Put 2.7 oz oatmeal in a bowl (2, 1/3 cup measures) and then add hot water/fruit mix.
Put in microwave for an additional 30 seconds. The advantage of heating the water separately is that mixing everything together and then heating increases the risk of the mix boiling over and making a mess. The final re-heat is to add some more heat after the cold meal and bowl chill the hot water.
Let the oatmeal/water/fruit soak up the water for five minutes.
Finally, I add a drizzle of molasses. I started doing that because I was not used to the taste of the flax-seed oil. Molasses adds a lot of flavor with a minimum of additional calories.
It is a fool's errand to list prices because they change rapidly, but at the time of this writing 2.7 oz of house-brand oatmeal is about twenty-five cents. Three ounces of raisins adds another sixty cents. The flax-seed oil adds about twenty-five cents.
Key point: the oatmeal is about 25% of the cost of the meal and my princely meal can be economized even more if things get tough.