For me its:
Gym wear: I find it fits better, lasts longer and doesn't get that weird spring onion smell that I can never seem to get out of cheaper stuff.
Shoes: After many years of many thousands of fast fashion pumps and ballet flats, I've started buying expensive shoes. They last, they don't generally leak, and they're comfortable.
Socks: Wider choice of pretty patterns, wash well and don't wear through as quickly as cheaper versions.
Knickers: I've spent too many years in generic, badly fitting, off the shelf under crackers. Now I invest a little bit more in no cross seam boxers. They're not enormously more expensive but my minge and my arse crack are thankful.
Cheese: Cheap cheese these days just tastes like a whole load of nothing so I invest in good, strong cheese that actually tastes of cheese.
Pies: We eat a lot of pie in my house 😬I find supermarket pies bland and not very 'filled'. We spent about £75/month on pricey pies nowadays.
Some alcohol: Some alcohol is definitely better when you throw some cash at it. Wine, mostly. Not all though - I can't tell the difference between Value vodka and expensive stuff. And Tesco Cognac is my absolute favourite even when stacked against very very expensive versions.
Squash: Once you've had Vimto squash (20p per 100ml), there's just no going back to supermarket own (6p per 100ml).
Foundation: Lasts and can actually be blended properly so I don't end up looking like a paint-by-numbers face mask.
What about you?