The books in the photo (children's books) are all from Best Buy and Sunday secondhand book bazaar Abids.
Shopping online is another convenient option. I've bought books from First and Second, Book Depository--this one has free shipping worldwide! how awesome is that? and then the Amazon. First and Second ships from India--I usually use amazon for International shipping when books I need aren't available in India.
There a few good Indian publishers for children's books and you might want to check them out. The prices are very reasonable too.
Ratna Sagar (school textbooks)