I have completed the GMAT and have scored a 730 (Q-49, V41) by using these and only these books that I mention below:
1. GMAT Official Guide 12th
2. GMAT Official Guide
3. GMAT Official Guide
4. Kaplan Premier
5. Manhattan SC Guide
6. Kaplan 800
7. Probability - An Introduction (David Santos) - I found this book to be exceptionally useful for probability
The free exams of Manhattan are still valid and are valid till April 2012, so there's a lot of time. I'm more than happy to share the username and password with you.
All of these books are in a very good condition as I respect the books I use, and I have not marked anything in any of the books.
I have spent roughly Rs. 6000/- for all these books (After discount). I am willing to sell these books for a small sum of Rs. 3000/-