It’s possible to buy bit by bit, week by week and start stocking up on ingredients until you have the basics.
i made a curry for four tonight with chicken, chick peas, fresh ginger, tin toms, tilda rice, naan bread and a spoon of garam masala (cost a quid) and the entire meal was around £8. It was absolutely gorgeous and I have left overs for lunch.
tomorrows recipe involves potatoes, chorizo, pepper, chilli beans and toms with sour dough bread and some chilli and paprika and will cost even less.
So in those two meals I have three new spices on the rack. It’s cheaper than getting horrible shop bought jars of sauce. It just takes learning - you have to learn how to cook. Time and effort.
my recommend is to always have butter (expensive but necessary) eggs, dried yeast and different flours so you can bake something; and porridge oats, potatoes, rice and pasta. Plus tins of beans, tomatoes, tuna and minced beef, chicken thighs bone on, good quality sausages or pork and breaded fish. Then fruit, salad and veg.
with that you can make tonnes of meals.
you can get that lot for £70. Best stagger it though and buy the dried stuff in bulk.