If you have an American Express card, you may want to login to your AmEx account and check to see if you have a Travel Reward, specifically:
Check your AmEx account to see if you have a travel reward with NCL for $125 when you spend $500 with NCL. (You can find it in your AmEx account under the "Rewards & Benefits" category -> Earn and Redeem -> Amex Offers -> Travel). It might also not be available to everyone. It's either their or it's not.
For me it's been 1 year since it last appeared. As final payment is due for this voyage in September, I contacted my TA and had them pay NCL $500 using my AmEx towards my remaining balance. The remaining balance will then be paid against my NCL BoA card in September, (unless I can find additional AmEx card holders with this deal also available who aren't using it (LMK)).
Safe travels,
- WYB