There is a good deal at $88 for one way flights between Los Angeles and Miami with several airlines for travel from December into March 2016. The reverse route from Miami to Los Angeles also has $89 flights. Finding the $89 deal with a single airline in both directions is more problematic, but if you don’t mind flying two different airlines each way, then there are plenty of dates for $176 round trip fares. United has dates with $97 one-way fares.
Sample fares for Presidents Week February 13-21. (Fare is $127 LAX-MIA one way on Sunday, Feb 14. I show Wed Feb 10 departure for $88 fare on Alaska Airlines for AA flight.)
LAX-MIA-LAX $176.20 Feb 10-Feb 20, 2016
Alaska Airlines Los Angeles LAX – Miami MIA (American Airlines operated flight)
$88.10 one-way Wednesday, February 10, 2016
Delta Airlines Miami MIA – Los Angeles LAX
$88.10 one-way Saturday, February 20, 2016