What's the best shampoo for color-treated hair on a budget?

Drugstore sulfate-free options like L'Oreal EverPure and Aveeno's oat milk line come up repeatedly in verified-purchase reviews as solid color-safe picks under $15. Salon brands like Pureology and Olaplex are better-regarded for heavily processed or very dry color-treated hair, but the gap narrows considerably for everyday maintenance.