Q: How much does warranty cost on dre beats headphones?

Here is some guidance but you don't say which country you are from.  If it is India, it is not included

http://uk.beatsbydre.com/on/demandware.store/Sites-beats-UK-Site/en_GB/Home-Coun trySelect

Are you purchasing them directly from Apple Store at http://www.apple.com/? If so, great news! All apple store purchased accessories such as the headphones come with a 1 year warranty at no extra cost.

And I mean ALL accessories, even the phone cases and the earpods, so go ahead and get your new pretty Rose Gold headphones