I read something several years ago from the Kings organization when the whole west coast AHL was still just an idea. They weren't concerned about the cost of the callups in real dollars (paying for flights, etc), they were more concerned about the salary cap impact. When a player is called up, or sent down, he starts counting against the NHL salary cap from the time they initiate the callup, not from when he actually joins the team. Same thing going down, in reverse, he counts on the cap until he returns to the AHL team. At that time Philly had their AHL team in the same parking lot as the NHL team. They were saving salary cap dollars vs LA who was paying at least two extra days of salary, or more if there was a delayed flight or complicated travel. The Kings had a few years where the were leading the league in games lost to injury. When you add that the cap dollars wasted across every player move it was enough impact on the cap to make it worth spending more real dollars to fix it.