Cheap is a relative word when talking about the Bahamas. That being said, it's my experience that the least expensive airfares, are available by flying into Nassau. More flights, and more carriers servicing Nassau.
The mile is an English unit of length of linear measure equal to 5,280 feet, or 1,760 yards, and standardised as exactly 1,609.344 metres by international agreement in 1959.
Statute Miles vs. Nautical Miles. A statute mile is 5,280 feet in length. A nautical mile is 6,076.11549... feet in length. To convert from statute to nautical miles a factor of 1.15 is generally used, even though it is not precise. (5,280 feet X 1.15) = 6,072 feet (4.11549...feet less than 1 nautical mile).You could add 4.1 feet for each statute mile to be converted.