I'm not sure about flights but we were considering going by train from Trivandrum to Goa last year and found out it takes about 12 hours. We didn't do the journey in the end but I don't think it's expensive. Any travel agent in Goa should be able to book something for you.

We flew down to Cochin a few years ago, spent two nights in a hotel there, and got the train back ( 2nd.class A.C.) It was a great trip,we saw all the sights and spent day on a Rice Boat on the Backwaters. Eddie at Daytripper organised the entire package and it went without a hitch, the train was a great experience. Cant remember the price but as it was prior to the Budget Airlines, it shoud'nt cost a bomb now We loved every minute of it and would reccomend it to anyone who wants to see some of the real India Alan