Hey,

IIT's give high-class education at subsidized fees. But still, it becomes difficult for lower middle class families to afford even the subsidized fee. Therefore, there are a lot of fee waivers are provided to SC/ST students(even 100%) and students from BPL families. SBI provides scholar loans to students who get into IITs - so one can earn and repay the fees to the bank after getting a job.

Fee Structure of IIT's
https://engineering.careers360.com/articles/iits-btech-fee-structure

All the best!