No need to weep you can book NCL freely with a US agent on a freephone basis & probably screw a bit of OBC if your cheeky enough. The problem comes from getting a late deal flight at the right price, as this can only be done Ex UK by yourselves.
These short cruises have always gone out of the USA at very low prices. This is mainly due to the restictions on gambling in the USA. Cruise lines provide the ideal way to get out of US waters and people can gamble away without the need to go to Nevada, New Jersey or the Indian reserves.