I think it all depends how expensive ingredients you buy, whether you rely on ready bits and pieces and whether you use up all the food you buy, including the leftovers. I would also think of meat as a flavouring rather than the main ingredient, bulk up further with low cost veg and pulses. Check kilo prices in everything you buy, I have been shocked how much cheaper it is sometimes to buy loose veg instead of packages, ditto grated cheese in comparison to a big block of cheese you grate yourself etc.
Pancakes (sweet or savoury fillings)
Soups with home made rolls + boiled egg for protein
Chilli con carne - I can make this go a long way as first serving with rice, then next day in wraps or as burritos. Finally, if anything left, will throw on top of nachos.
Sausage pasta (insides of 2-3 sausages go a long way for flavour)
Pie - can hide any sort of leftover bits in pies for random mix, if you are okay using cheese then cheese kind of puts it all together. Super cheap if you make the base from scratch.
Oven toasties from leftover bits of bread, some tuna, cheese etc, home made potato wedges instead of chips.