[08/27/2019 @ 02:53 PM CT] Still available. Updated example dates.
Delta has round-trip flights from Milwaukee (MKE) to Liberia, Costa Rica (LIR) for $340 with a connection. Flights September to October. Weekends available.
Note: Carry-on bag is allowed for free on Delta. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.