Neat site, I'll bookmark it..
I booked a trip for the last 2 weeks in June in Panama. I depart from Calgary also.
I've used this consolidator for 2 int'l flights before this and they've had (what I thought were) pretty good prices:
www.flightnetwork.com
My return flight to Panama through Flight Network is $1,020 (all taxes & fees included -- $914 before all that).