Veer Design Studio have awesome options in the light lehenga section that costs as low as INR 10,000, which I really liked.
This Lehenga Store In Santacruz Has Affordable & Stylish Options
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What Makes It Awesome
I saw some really good sister of the bride/groom outfits all under INR 20,000, and even better exclusive bridal wear all under INR 40,000.
Pro-Tip
Also, they have an online store, here's the link. You can check out their collection before visiting them.