I call it frugal. I suppose you could beat school lunch prices with a daughter that eats light, but I have a 15 year old boy that is 5'11" and goes 190 and a 13 year old that's 5'8" and 160. A half sandwich and some fruit ain't gonna cut it. We pay $100 for about a months worth of meals. There is no way I could pack lunches for that. Even if I wanted to pack them leftovers they now eat everything I make for dinner. I'd have to make extra just to have left overs.
I have a hard time believing that you can pack a lunch for under a buck that's going to be better than the school lunch. With the cost of fresh fruit and vegetables, milk, etc., I just doubt it can be done, even for a 5 year old, much less a teenager, even a girl.