IIT Bombay, Delhi, Guwahati, Kanpur, Kharagpur, Madras, Rookee. 
The maximum salary of a student from any of these IITs has gone as high as 50 lakhs per annum or even higher. 
The minimum salary may go as low as 4 lakhs per annum or even less. 
Few students can't complete there degree and come out of the college with nothing.

You should never estimate the caliber of an IIT student by the salary he/she gets 
or even by his/her grades in college. 
If you want to do engineering there is nothing better than it (in India) so it is the best 
possible you can try for.

This year the highest salary offered at IIT campuses were 75 lakhs per annum but that 
was in Computer Science domain and the salary of Mechanical Engg. student is 
between 5 lakhs per annum to 50 lakhs per annum.