I have bought silk saree from few shops there but these two are my favorite.
Varamahalakshmi :
They have sarees in all ranges and all categories. If you want loads of options to select sarees from go to this place. They have so many colors and designs in silk sarees. I got these sarees from them.
P.R Krishna & Sons :
This is a small shop, they bring sarees directly from their own silk loom so the price is quite less when compared to other shops. They have hand picked collections. If you want any custom made silk saree this the place to go for. Go to them with the design and color of your choice and they will make your dream saree within 2 weeks and the price is also quite reasonable.
Have you bought silk sarees from Kanchipuram ?