How to find a Vedic astrology book on Internet?
You might be aware of YouTube.com, a popular website for sharing videos. On the same line, there is a website http://www.scribd.com/ for sharing documents. On this website you get almost all classical texts and lots of new books on vedic astrology. This website is not just for astrological books, and like youtube, you can search document on any subject here. I believe it also allows you to download the document for future reference. Like YouTube, it also has a related document section, so you will find similar files on the right pane. For example, I searched for Saravali, and also found Phaladeepika, Bhrigu Sutram, Brihat Parashara Hora Shastra etc. in the related documents list.
Here are the direct links to some of the classical books on vedic astrology
Kalyana Varma's Saravali
Brihat Parasara Hora Sastra
Jaimini Sutra (Commentory by Bangalore Suryanaran Rao)
Some of these documents may also be of your interest -
Mantras and remedies for the nine planets
Jyotish Alpha & Beta
FAQ on Retrograde Planets
Loss and Gain in Career
Sri Yantra and Sideral Astology
Effects of Navamsa