I used to make my own lunch from either the previous night's leftovers or mix and match sandwiches from whatever we had in the fridge. Sometimes I would buy a cut madeira cake from Coles and slice it up to last the week for morno's along with some fruit. You did what you had to do.
It would not be hard to spend $100+ per week buying take-away for lunches.
I can do 5 morning teas and lunches for work for $30 or less, especially when I use leftovers.