Yes! Cosmic does have KTM-DEL flight everyday and at different time periods and it costs around Rs. 5000 one way (not sure abt two way)....but he main problem is they have small jets (MD Mcdowell type), so, they just allow one suitcase per passenger (not sure about the weight limit).....as opposed to two piece luggage per international passenger.

So, learn abt all these stuff carefully.

Good Luck!