Among stereotypical breakfast foods is one that provides a great opportunity to eat healthily at a low cost: oatmeal. This is a whole grain food that should keep you feeling full through the morning, and it is very inexpensive. I typically buy the big store-brand canister of quick oats, which is $3 or less for 30 half-cup servings. That's 10 cents per bowl. It takes less than two minutes to prepare.
Now, you might say, "But I don't like the taste of plain oatmeal, and I'll go insane if I have to eat it every day." Here are some things I often add to my oatmeal to help it taste better, and you can mix and match for variety:
Cinnamon - zero calories, costs a penny per breakfast
Apple, half, sliced - 40-70 calories, ~$0.40 (varies by size & price)
Honey, 1 tbsp - 60 calories, ~$0.20 (highly variable)
Walnuts, chopped, 1/8 cup - 50 calories, ~$0.18 (@$4.50/lb)
Grape Nuts, 1/8 cup - 50 calories, ~$0.16 (@$2/box)
Flax Seeds, 1/8 cup - 90 calories, ~$0.15
Banana - 90-130 calories, ~$0.25 (@$0.69/lb)
Sugar Substitute - 0 calories, a few cents per packet or free
So, you can have a variety of pretty healthy and tasty breakfasts for $0.50 or less. I even splurge sometimes and have a $0.75 bowl of oatmeal with banana, honey, and walnuts.
Even throw in an 8oz glass of delicious Tropicana orange juice (they do not pay me) fortified with calcium and vitamin D for $0.40 or less. I refuse to pay more than $0.05/oz for juice, and it goes on sale often for less than that. There's a nutritious breakfast for less than $1 per day per person with only a couple minutes of preparation that even a child can handle.
This is a great option for those of you with kids. This kind of breakfast will help your children concentrate at school and be healthy. It doesn't make sense to pay more money for junk cereals that are half sugar, or Pop Tarts, or whatever else, which lead to poor concentration, obesity, and potentially type II Diabetes.