NCERT is more than enough for cracking NEET . You can score very good marks just by studying NCERT textbooks for classes 11 and 12 they cover the whole syllabus of competitive exams . All you need to do is go through each and every page of the book. Even the small details and examples . 80% of questions are asked directly or indirectly from NCERT. So if you read it thoroughly line by line, it should be sufficient. Also refer to NCERT exemplar. You don’t need to get expensive guides for that.
However, to be on the safe side and to ensure a high score that guarantees a seat, you must refer to some other advanced books that provide detailed and in-depth explanation of all the concepts in the syllabus of NEET.