IanCarb

NCL charge 2-3 times the actual cost of airfares, not a reduced fare! Book directly or through your travel agent, and get more flexibility and full choice of hotels and durations.

An example might help clarify. Say you paid 3000 for an Inside, when a Balcony would have been 6000 at that time. Later, the prices reduce to Inside 2000 and Balcony 4500. You cannot get a refund of 1000 to stay in the Inside. If you want to upgrade to Balcony, the charge will be 4500 (new price) less the 3000 you've already paid, ie 1500 to pay. You can see the prices online, but will need to phone to make the change. As far as I know, it does not depend whether this is before or after the final payment date. That is, you can take advantage of the lower price if you take an upgrade and spend more money in total.

NCL aim to take as much money as possible. If you make a high bid you might get it sooner, but otherwise you and everyone else will wait until NCL decide they're unlikely to sell it to someone else. The whole process is biased in NCL's favour, of course

The price will be the same online as phoning in. But there are important differences. Phoning, you're likely to get a quick run through the multiple options (often with very similar names), and pressure to decide. Prices are held throughout your call. You can choose any available cabin with the grade. Online, you can take your time. Prices might keep changing. You can see exactly what you're thinking about. But you'll be given the first cabin in the new grade, without even knowing which others are free. Best likely to be deciding online what you want, but phoning to actually book it. But be careful not to block yourself by holding a cabin online, preventing you buying it by phone!

What do you mean 'on site'? On the ship?