Hey Harsha,
Sorry I couldn't reply any sooner. Here is what I suggest:
I: NOVA is good and inexpensive (Rupees 295

). If you have the time I recommend NOVA's Quant section.
II: Also, if you are not lazy like me you can start maintaining an
error log (unless you already do). I didn't maintainan an
error log myself but I would mark questions I found tough or I did wrong in the book itself. I would regularly go back to these questions.
And most importantly,
III: Master the concepts. A 600 level question is not too different from a 700 level question. If you can solve one you can solve the other. A 700 level question will be presented to you in a way that will probe deeper into your understanding of the same concepts. Here's one way to test if you have mastered the concepts fully - Do you frequently go wrong while solving a Quant problem but the solution offered or the OE makes sense to you when you read it? Then you need to work on mastering the concepts.
Start by participating in the Math Discussion forum here and by studying the Advanced & Intermediate Math sections on this site. Don't shy away from posting your comments, offering a solution, asking a question or questioning other's solutions. Remember you learn more from the mistakes you make and the Quant guru's on this site are the ones who have made the most mistakes.
I didn't use Kaplan 2005 or Kaplan Math Power but OG 11 is good, especially the DS. Work with the GMATClub challenges. I only bought Question Collection 2.0 but those questions test concepts in a challenging way.