One thing I'm enjoying at the moment is spaghetti with a sauce mad from blended 'Super speed' soup. (You can find the recipe if you Google it) I know the initial cost of all that veg can be steep but, if you shop at Aldi or equivalent, it is much cheaper. I found that when I made it, it made a huge, huge amount, enough for four big bowls and two big Tupperware containers filled and put in the freezer. I took out about two bowlful sand blended it then spooned a ladle full into several plastic freezer bags ready for use whenever I fancy it. I use 15g of cheddar and 15g of Parmesan mixed in as my healthy extra a and it tastes just like the fresh tomato and mascarpone pasta sauce you can buy from the supermarkets. the best thing is, it is completely free!
another option is good old sausage, mash and beans (use low fat sausages) or spaghetti bolognaise with extra carrots, mushrooms etc to pad it out so you need less of the expensive meat. I often make a risotto too, using bacon and mushrooms, onions, peas, with a little lightest Philadelphia mixed in. You can use ordinary rice instead of the special risotto rice as it is much cheaper.