What's the flight or flights that regularly connect an European Union country with India for less money? My research has showed that Air Arabia was a good option some years ago when connected Athens with a lot indian cities through Sharja, but now this route is no longer operated.
I am not sure whether it is the cheapest, but Emirates currently has offers from many European cities to Delhi, Kolkata, Bangalore, Mumbai or Chennai for 550-600 Euros return. You have to change in Dubai.
You can fly from Madrid to Delhi on February 24th for 464 Euros.