I would double check your pricing on the NCL site. They have changed how the price is calculated. It isn't until you put your full information in do you see your actual price (that includes port fees, taxes, etc.) Your TA can give you the free at sea and the price should be identical if not better (depending if they have group space allotted.)
See the little tiny note they have now under the subtotal
"Excl. taxes, fees and port expenses, they will be added at checkout."