I make my own Nancy Birtwhistle laundry liquid, limescale remover/toilet duck and window spray. Something like 80% reduction in cost, eco and more efficient cleaning.
Washing up liquid is the cheapest I can find and I use it with gay abandon! I only wash pans by hand and the eco stuff wasn’t good at cutting through grease.
No more fruit yoghurts in wasteful tiny pots, just jam on 1kg Lidl plain Greek yoghurt that does for cooking and baking, too.
Lidl fine porridge oats are almost as good as Quaker at a third of the price.
If you’re putting time and energy into creating a tasty meal, you can start with basic products like cheap dried herbs, pulses, flour and rice. No need for spice packets and cook-in sauces. Mutti tinned tomatoes are great but cheap ones are fine for lasagne.
We’ve also done away with vegetarian meat replacements like “bean sausages”. You always feel cheated. Just make real food, and if a recipe calls for something expensive, use an alternative (eg. turmeric instead of saffron, frozen peas instead of fresh asparagus).
I still buy plain cheap cakes like sponge or marble cake (not Mr Kipling syrupy waxy stuff) because my time and ingredients would cost more.