It's depends on,how you want to enjoy your trip.. there are so many places in India like,
Andaman
Ooty
Hampy
Lonavala
Pondicheri
Goa
Dalhousie
Mcleodganj
Manali
Kasol-Tosh
Ranikhet
Nainital
Shimla
Derahdun-Mussouri-Auli
Haridwar-Rishikesh
Sikkim
Arunachal
Meghalaya..
15k will be a standard budget to visit anywhere in India.