depends on where you are, but Kolkata has open markets and I just go there, when I'm back in India. Delhi is great for textiles, and Mumbai I like to follow this brand that repurposes deadstock fabric into fun accessories - https://www.instagram.com/juhubeachstudio/
There's also tons of home-grown stuff of course, India IS the de-facto source for so much textile and craft; No Borders for example sources a lot of cool vintage pieces, and houses local designers to browse from.