Hello,
First of all, keep NCERT as your basic book. Read and understand it thoroughly. Further for reference, you can go for the following books :
- For physics — Fundamentals of physics by Halliday, Resnick and Walker
- For chemistry — ABC of chemistry for class 11 and 12 by modern
- For biology — Trueman’s objective biology for NEET by MP Tyagi
Also, I would like to suggest you a website which offers second hand books, free of cost. It is a very trusted website called MyPustak. You can buy any book from it absolutely free of cost and the books will be delivered right at your doorstep completely hassle free.
You can also donate your old books to MyPustak and it will furthermore give those books to people in need. This organisation pickup the books from their respected donors (who have contacted MyPustak for donating books on their will, contributing to many), gets a quality check if it’s in good condition or in a state that it can be re-used and then only, they put it on website for others to buy and use it. And this is one of the many reasons for why MyPustak offer Free Books.