For setting up a bitcoin exchange you would need to know if you wish to go the traditional way or the decentralized way. Both have pros and cons.
You can get a white label exchange created by Indian providers or foreign companies. The cost will vary as per your choice.
I rely on Xpesa as its the best with more than 100 years of experience in a bitcoin exchange, cryptocurrency exchange, buy sell bitcoin, Bitcoin Cash, and Ether. Also, it is free of cost and the only platform that gives such services with zero fees