Let's be honest about what you're paying for, because the marketing won't be.
The single biggest thing expensive paint buys you is pigment. A tin of Farrow & Ball or Little Greene Intelligent Matt is loaded with more pigment and higher-quality binders, which is why those colours have a depth and a way of shifting through the day that cheaper paint just can't fake. Mole's Breath, Cornforth White, Setting Plaster — these have a complexity built from multiple pigments that a budget tin flattens out. If colour is the whole point of your scheme, that's where the money goes and it's worth it.
Where the gap narrows is everyday performance. Dulux Trade and Crown Trade are seriously good paints — durable, washable, dead reliable, and a fraction of the price. For a rental, a hallway you'll repaint in three years, or a ceiling nobody looks at, you do not need a £60 tin. Dulux Heritage gives you that designer-colour depth at a kinder price than the boutique brands, and it's a genuinely cracking middle ground.
The "but what about coverage" question matters too. Premium paints often go on in two coats where you'd need three of something thin and cheap — so the per-litre price isn't the true cost. Factor in your time and a second tin, and the gap shrinks again.
My honest take: spend on the rooms you live in and the colours that carry the scheme — a feature wall, a drawing room, a kitchen you stare at every day. Save on ceilings, cupboards under the stairs and short-term jobs. COAT and Lick sit nicely in that value-conscious-but-still-lovely bracket if you want decent colour without the F&B premium.
Prep is the real money-saver, by the way. The best paint in the world over dodgy walls looks like the cheap stuff. Spend on filler and sanding, not just the tin.