Let me be straight with you: nothing in the budget brackets gets properly close to Little Greene Mid Azure Green. The nearest we can find is Dulux Heathland (LRV 3.8) at ΔE 7.8 — and anything above ΔE 2.5 is a perceptible difference, so that's not a dupe, it's a different colour in the same family. On a feature wall, side by side, you'd see it.
The other contenders drift further still. Crown Racing Green (LRV 6.2) lands at ΔE 13.8, and COAT Ditch the Tie (LRV 8.1) at ΔE 13.3 — both are recognisably their own deep greens rather than stand-ins for the Little Greene shade. COAT's worth knowing about generally because it's a cracking eco-conscious paint with a lovely flat finish, but it isn't doing Mid Azure Green here.
So what should you actually do? Two honest options.
If it's *Mid Azure Green specifically* you've fallen for — that deep, slightly inky teal-green — just buy Little Greene. The pigment load and depth in those dark greens are part of what you're paying for, and a near-miss at ΔE 7.8 will nag at you forever. For a single feature wall the cost difference is modest in the scheme of a room.
If you simply want *a* deep green and aren't wedded to the exact tone, then Dulux Heathland is a perfectly good colour in its own right — order it as the right thing, not as a compromise. It'll go on beautifully and cost you less.
Whatever you choose, get a proper sample pot and paint a decent patch — at least A4 — and live with it across morning and evening light before committing. Deep greens shift dramatically between daylight and lamplight, and that matters far more than chasing a ΔE figure on screen.