If you make the bread yourself (i.e. with a breadmaker) it's dirt cheap. I buy flour and yeast in bulk and it costs bugger all per loaf.
You could maybe argue bread isn't healthy because it's technically a processed food (flour, carbs, etc.), but as others have pointed out moderation is key.
I was looking at similar requirements for my daily lunch during the workday. I live in London so you're paying between £5 and £10 per day even for just a sandwich-based lunch. I needed a packed lunch that was cheap, tasty, healthy and additionally: filling, easy/quick to prepare and low carb. So that's a big ask.
I settled on a kind of custom Greek salad. One cucumber, some red onion, pickled beetroot all diced up, olive oil (or cold-pressed rapeseed oil) and some feta cheese. Sometimes I add chickpeas and coriander.
It's perfect, I've been eating it for years now.