Colleges in Indore

It's around INR 80k-120k for the full course.

Prestige is a really good college. The campus is decent teachers are very friendly. Great chance of getting good placements and overall a good environment with great scope for personality as well as overall de development.

Cut off in AIR doesn't really get affected much but you can always wait for last round of counselling. It may go down if students leave the college after first round.

http://www.targetadmission.com/colleges/1232-shri-gs-institute-of-tech-science-indore#fees
You can get idea of fee structure by this.
Normally, closing rank for general category students is 35000-40000.

If you are an Indian resident then you can give CAT entrance exam. If you are an NRI then you can apply using GMAT.
IIM Indore gives different weights to 10th, 12th, CAT exam in the selection of candidates for its MBA programme. You can check them here: http://www.iimidr.ac.in/academic-programmes/post-graduate-program-in-management/pgp-indore-admissions-details/

CAT is held every year around the month of November. It contains 3 sections namely, quantitative aptitude, data interpretation/ logical reasoning and vocabulary part. You need to clear different overall cutoff and sectional cutoffs for different business schools. It is a relative exam which means that your performance is judged in comparison to the performance of other candidates.

I would encourage you to get your NCERTs and RS Agarwal sorted out for reasoning and competitive exam. For Verbal Ability, refer to Wren & Martin or some primer like McGraw Hill or Pearson. Solve a lot of mock tests and practice a lot of questions.
For the interview, prepare well about your background and also about the subjects in which you have high marks. The panelists are mainly interested in screening your confidence. You must definitely try to give some mock interviews.