Dear Rahul, Goa is a good choice, and Goa also provides lots of choices. Cost always depends on your preferences. Since this is a off season expect around 1000 - 1500 per day for a good clean place. Contact Seldon Fernandis : 7507648918. He has a range of options to choose from, from double bedroom to sea facing villas. Happy Goa time.
I just did Goa with my friends last week. It costs around 10k per person. We stayed in Condolim and Varca and it costs around 2400 per person for 4days. We ate lot of sea food in various restaurants and that comes down to 2500 per person. We rented 5 scooters from Madgao and it was 400 per day plus fuel cost extra. Apart from that some miscellaneous cost also there. We did parasailing for 1k on Colva beach. Since we were 10pax amount got divided. It may increase for you if you go down as a couple.