You need not worry about your fees as in most NITs, full remission of the Tuition Fee is there for General and OBC students whose family income is less than Rs.1 lakh per annum. But you have to take care of the annual fees and hostel charges.

For example -

NIT Warangal

Tuition Fees            0 (in your case)

One Time Fees    24,500

Annual Fees            7,500

Hostel Seat Rent (per Year)    5000 (Boys) and 2000 (Girls)

Electricity & Water charges (per Year)    5,500

NIT Surathkal

One Time Fees    5,250

Tuition Fee (per Semester)    0 (in your case)

Other Fees (per Semester)    2,100

Annual Fees    13,030

Hostel Seat Rent (per Semester)    6,300

Mess charges (per Semester)    10,700

Mess Advance (per Semester)    18,000