...Saba is a different league...I realize it's big chunk of change, but you are so close! Will you go back simply to dive Saba?...
I had the same thought. If it is likely that you will get back to Saba some time in the future then you should just wait until then. But if you think that you probably won't get back then perhaps you shouldn't miss this opportunity.
If you won't have to make non-refundable reservations then you might make the arrangements with the option to cancel if the weather isn't great.
Have fun!