what i think is that buying books is not as important as your knowledge!
What you require the most is your ability to analyse and apply the concepts that you've learnt.
The books that you have are much more than enough for getting a decent rank in IITJEE.
Now the only thing is that you havent joined any coaching classes as it seems then you'll have to work a bit harder to get things into your mind. Once this is done and if you have practised several problems (be it from any book that you have) then you surely to get a good rank!! Even i am preparing for IIT and this is what my Sirs have told me! Still you wait for sumone else to answer your question so that you're sure of what you asked !!! :)