Mansi CAT exam is the only way to get into IIMs. You will need to appear in CAT'18 and then only according to your score you will get calls for the second round of WAT and interview and then next year only you can get admission. Through CMAT you can get admission in other b-schools according to your score.

For your other question if you mean MBA IT fees, then it varies from college to college from a range of 20 thousand to 20 lakhs. Generally better the college higher is the fees and better is the placement. FMS Delhi is an exception whose fees for MBA is only 20 thousand for two years.