For 2 adults 2 children in a balcony stateroom, I heard it works out to around S$3,000, S$3,100 total, though some promos can bring it lower, look out for the "3rd and 4th guest sail free" deals which really help with the kids' fares. My neighbour booked during a travel fair and got in at around S$295 per person for the base cabin, so timing your booking makes a big difference.