One can just about walk around the entire island in one day.. so there is little need for a taxi.  Use a taxi between airport and motel and the day motel to airport.  The locals hitch rides when they're travelling across the island. The first car with room will usually allow you to hop in the back...hitch to and from the shore when you grow tired.  Walking around Saba stretches the calves--lots of little hills. Don't miss the Sandy Trail which takes you through the rain forest.