I am guessing they want the price to the water taxi, which I am guessing is about the same. Don't know where you are traveling from, but taking the taxi, water taxi, etc. makes for an even longer travel day. I always suggest the flight directly from International, even though it will cost you about $15 US per person more than what you are planning, after getting up at 2:00 am to catch a flight, then another flight, and sitting in airplanes and airports all day, it is well worth it.
JMO