Tough question to answer. Certainly you could do it cheaper in the Keys since you have your own boats. And there is a lot to be said for fishing off your own boat and all that goes with that.
But the flip side is that it depends on how much you want to catch fish. You are simply going to catch more fish in the Bahamas. Even hiring a guide for a day or two in the Keys is not going to prepare you a lot for the waters. Sure beats totally going blind but two days is just a start to learn an area.
Sorry to not have a concrete opinion but it really boils down to which approach will float your boat more (sorry couldn't resist
Is it more fun to get into a bunch of fish or more fun to have done it on your own. Answer that question and then you will know which way to go.
Good luck and FWIW neither one is a bad approach!!v