The Inderlok street market is one of the best haunts to shop fabrics, semi-stitched suits, and clothes from. Situated right below the Inderlok metro station, across the road from McDonald's, this market is quite popular (the inflow of people who come to shop here every Thursday is a testament to it).
The Inderlok street market sets up shop every Thursday morning, around 9 am. It stays put till about 4 pm and then, the sellers disperse. You can find anything from whole fabrics, Banarasi silk dupattas, chikankari palazzos, crockery (mugs for INR 50 each) to semi-stitched suit sets with pretty gota and zari work, and heavily embroidered saris. What makes this market tempting is the quality of the goods you get at such affordable prices.
The Banarasi silk dupattas that I just mentioned, come in wonderful colours like rani pinks, graceful greys, lemon yellows, and bright reds for only about INR 300 per piece. You can even get larger pieces of Banarasi silk fabrics for about INR 250 per metre (not sure if this will be pure silk though) and make a sari out of it (or whatever you like).
The semi-stitched suits you get here come with palazzos as well, all for around INR 2K each (depending on the work done on them and the fabric quality).
The Inderlok Thursday street market is one of those markets that you should go to maybe 5-6 months ahead of a family wedding or party, because they mostly have fabrics and semi-stiched clothes, and it will take time for them to be ready and tailored to your fit.