If you are looking for very old books or non-run-of-the-mill books, you should check out "Select" book shop, off Brigade Road. It is at the end of a small lane off the side of the Brigade Road that has KFC, Radio House, Scullers, Barrista, etc. This book shop is not very well known, especially among people new to Bangalore, but it has a treasure of remarkable books that are very hard to find, let alone buy, anywhere else.
Some blurb on this book shop:
http://www.hinduonnet.com/thehindu/m...0800400300.htm http://www.hinduonnet.com/thehindu/l...0600400600.htm http://www.hindu.com/2005/07/30/stor...3001910200.htm