I recently bought few Tamil novels using Udumalai.com. I am able to find the Tamil books what I want to buy which is usually not available in any other online shopping portal.
There is also a option to pay at cash on delivery, so there is no need to worry about your money and reliability. And they also delivered books without any transport damages. I prefer this Udumalai.com to buy Tamil novels. In this website they are also selling footwear and apparels.