This article has some interesting info on
Virgin Blue. They run 50 planes at $130 million profit pa. That's about $7000 profit per plane per day. If you make 7 trips per plane per day (my guess) and you use the planes every day of the year, that's about $1000 profit per trip. Even if you only make half that number of trips per day (say 3½ to account for down time) that's about $2000 profit per trip. I have no idea what the costs are but that seems like a pretty small profit margin to run a plane.