I went to Kaplan Advanced
course for GMAT and found their books very useful. I also have almost all of Manhattan's GMAT book. A brand new OG 12
and a used OG 11
. I can also chip in and sell RC 99.
books that are used in their classes are very different from what you see on stores. The course costs 1500$. This book was very useful for me. I'm sure it will be helpful for you too. Send me a note if you are interested.