Are materials to build rocket oven easily available where I live?

I live in India, are the materials easily available here, or I need to do something else?

First, welcome to permies!

India is a huge country with a robust manufacturing sector--so all the components are available in the country--but whether they are available in your local area is a question I can't answer. A steel drum and rockwool are the most essential components, and the rest can be made out of a variety of materials. Have a hunt around your area to see if you can find or order those. If so, I'd go ahead with the project. Best of luck!