I honestly don't now where to get fins or this board. I would look at some reasonable cheap surf fins, ie side biters for a longboard. The Star Fish is a very riding oriented board and longboard sidebiters will work well for wave riding. If speed and B&J is your priority you'll be better off with the center fin only anyway, I would say.
Since you will be sailing with a big central fin, the force on the sidebiters will not be that bit, so fcs fins wil hold up fine. After all, good surfers are putting those through their paces pretty heavily. Adn if you hit something, it is better to break the fin than the box.