Not an OBC, but a savings:
Target - buy Disney Gift Cards with Target Red Card and save 5% at checkout. E-mail ”cards” can be bought in multiple denominations.
Sam’s & Discover Card - $75 packs of gift cards are sold with a 4% discount (larger denomination cards offer less savings). Currently, Big Box stores are the quarterly 5% Discover cash reward category.
I’m thinking you probably don’t need to pay off your cruise at this point, but getting the gift cards to cover gratuities, port adventures, Palo, ... is just a little more money in your pocket.
Bon Voyage.