Kovalam is about 16 km 20 minutes in a taxi from Trivandrum. Taxis can charge around 400-500 rupees to get to Kovalam. When asked where you want to go, say Hawa Beach, Leela Beach/Main Beach or Lighthouse Beach in Kovalam.
In an auto-rickshaw 150 - 170 rupees is a fair price, avoid going above 170 rupees. If in doubt ask to use the meter, but in reality they really don't work at all. Advice being if they are trying to rip you off go to leave for another rickshaw and they will often back down and offer you a fair price, if not, get in a different rickshaw. Even if India is a cheap country, the prices for gasoline are international standard, so don't expect super cheap private transportation. If you go by public bus from Trivandrum-East Fort to Kovalam Beach you only pay 8 Rps. for the half hour trip.
Buses to Trivandrum can also be caught from Kovalum Junction as well as Ambassador taxis and Autos to pretty much anywhere.
Be very careful walking around the junction, especially at night, as there are no traffic lights what's new?! and the street lighting is very minimal. The intersection can be busy.
