I've been turning this over in my head as well. We don't have Costcos where I live yet (lots of Sam's Clubs), and we love our TA but her agency does not offer OBC, which is frustrating.
We usually do 7-night E. Carib. Fantasy cruises, getting two standard Cat 5D verandah staterooms. For the five of us, the fare is roughly $8000.
But using Dreams as a "stand-in" agency (i.e., one that offers OBC), it seems like the question is which is the better deal - the full OBC through DU, or (the 50% OBC through Dreams + the 10% OBB discount + the $200
DCL OBC). Am I looking at it the right way?
So, if I book straight through Dreams for an $8000 cruise, I get no discount, but will get approximately $400 in OBC.
If I do OBB, my $8000 cruise becomes a $7200 cruise, plus I still get $400 in OBC ($200 from Dreams OBC, plus $200 from DCL).
If I have all that right, then for my usual cruise, the OBB is the clear winner, no?