AeroMexico via Orbitz have a $150 roundtrip airfare from Los Angeles (LAX) to Panama (PTY) including taxes and fees.
Departure: February 7-10, March 1, 2
Return: February 20-22, March 9-11
Use those dates and book it on Orbitz but be aware this may cancel.
My sample travel dates: March 1-9, 2017