Iceland BIG (1.5kg) lasagne - £3, feeds four people quite comfortably and doesn't actually taste bad at all. Not a clue on the nutritional side of things.
Make my own lasagne - approx £6 just for the beef, £1 for a couple of cartons of passata, store cupboard basics for bechamel sauce (flour, milk, butter, cheese), a couple more quid for the lasagne sheets, 50p for a big onion. Additional veg (peppers, mushrooms, courgettes) optional.
It usually takes me about an hour to prep all the ingredients then 30 - 40 minutes to cook. Bound to be more nutritious than a frozen version but it had bloody better be for the prep time and considering that it costs easily 3 - 4 times as much.
Save money by swapping beef mince for quorn mince and save time by buying the sauces in jars (yak, imo, but each to their own).
We make a lot of pasta bakes. A 500g bag of wholemeal pasta is 95p in Tesco and makes enough to feed four with leftovers (handy for lunches the next day). Chop up an onion and a couple of cloves of garlic and fry lightly. Add two cartons of passata (about £1), whatever herbs and spices you fancy and cook for about 5 minutes. Take off the heat and stir in two tbsps of cream cheese (I use quark) then mix through the cooked pasta, top with grated cheese and bake in the oven for 20 minutes.
Again, no idea on calorie content but it's very filling and much tastier than any microwave pasta bakes I've tried.
That hasn't answered the OP at all, has it. I dunno... it is possible to cook all your meals from scratch without spending a fortune but it depends how much meat you eat and whether you're prepared to stick with a handful of tried and tested recipes to batch cook and reheat when required. Variety and using lots of meat is what makes is expensive in my experience.