Do you eat other kinds of meats? What kind of fruits and veggies do you eat?
I really like making quiche with egg whites.
Spray cooking oil and coat a muffin tray lightly with bread crumbs. Then mix 4 egg whites, 1 cup of veggies (onions, mushrooms, and spinach are my go to), 1/2 cup broiled chicken breast, 1-2 Tbsp of light cheese, and about 2-4 Tbsp of milk (Avoid overly liquid, but just enough that it's not just globs of veggies covered in egg). This usually makes about 4 muffins and you can mix and match anything with it. Just bake it on 350/175 for about 30 minutes until they're not wet anymore.
Special K is also kind of expensive (at least here) Maybe you can make breakfast cheaper by substituting whole oats, with nuts and berries? It might bring your overall cost down and again- you can switch it up. There's also plenty of recipes online for homemade granola if you really want a cold cereal.
Out of curiosity where is your fats coming from? Tuna has a bit and bread has a little but I don't see much other fats. Make sure you're getting good fats because your body does need them- oily fish, avocado, coconut, nuts are really good sources. Just add a little bit of nuts to your breakfast or avocado on a sandwich. Lately I've been chilling coconut milk and adding it into a smoothie to boost up my daily fat- it works beautifully with a little bit of mango and banana.
Soups can also be a good light meal. Not sure what to recommend, but it's something to look into.
Ducky gave you some good information. If you opt for soups, make sure they are broth based, not cream soups, as the cream soups have far more calories.
You can actually eat most things, so long as you watch "bad" fats and maintain portion control.