Taxis are cheaper and faster than transfers. Make sure they use their meter and the setting should be #1 for daytime. They also add a supplement of about 2.1Euro for going to the port and 1 Euro for each piece of luggage in excess of the first piece. Your final price should be approximately 30 Euros (as you had heard). Taxis are clean, fast and usually honest. You might be able to get a van/taxi at the airport that can take your entire party. Just ask at the taxi stand and they will get you a van if there is one in the queue.