Nonstop round-trip flights from Austin (AUS) to Fort Lauderdale (FLL) are on sale for $177 right now. JetBlue is the operating carrier. You should probably get a rental car and take the 25 minute drive for a Miami side-trip. Take the A1A all the way down to Miami Beach, stopping wherever you think looks like fun along the way.
[09/07/2014 @ 9:48 PM] Removed due to lack of availability on most days.