While I personally would not recommend this airline (had a very bad experience with them back when Mills did that show at The State a few years ago), it's hard to argue with $9 each way (on certain dates):
http://www.spiritair.com/welcome.aspx?pg=salesinformation&number=78 "The $9* Sale! In celebration of Spirit's new service to the Caribbean, we are offering fares on many of our flights from an incredibly low $9* each way!" So, if you live in Detroit or Chicago or NYC or Atlantic City or Providence or Orlando or Washington DC or Ft. Lauderdale, and that latest Deepchord CD has you dreaming of Dub and spliffs, now's your chance :-) - Greg