One of the cheapest trips I recommend are cruises. This is only $129 and departs Miami.

Ports of Call: Miami, Florida; Nassau, Bahamas; CocoCay, Bahamas; Key West, Florida; Miami, Florida

2008 Departure Date(s): Nov 17, 24; Dec 1, 8, 15;

2009 Departure Date(s): Jan 5, 12, 19, 26; Feb 2, 9

2010 Departure Date(s): Jan 4, 11, 18; Feb 8, 15, 22