Their (oh so poor..) website has very interesting fares on Mancester - if you want to do a day return next Wednesday for example, they look for £249. But if you book IOM-MAN departing at 0805 with a throwaway return in July, this will cost £69.00. Then book a Manchester - IOM (last flight) with a return in July and - hey presto - it also costs £69, giving you a total cost of 2 x £69 plus an extra round trip in the summer if you want it. Even if you want the flexibility of changing the return from Manchester, buying a third ticket this way still works out cheaper than the £249. Back to backing is still alive and well!
My math may not be what it used to be, but I reckon it would take a lot of passengers to cover the cost of even a Chieftain or Jetstream at these levels....