For goodness sake - how on earth do you expect anybody on a public forum to know where you can buy iPhone batteries in India? If you are there it is up to you to find out and someone here might be posting from the US so would have no clue.
If you are in India, then it won't take you long to find out - perhaps an Apple re-seller or a phone carrier shop would be a good place to start!!
This site contains user submitted content, comments and opinions and is for informational purposes only.
Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site.