I'm not sure they are actually trying to sell them, you can buy Mustangs much cheaper than that. It is more likely that they are using the aircraft as a carrott to attract some potential owners for the surplus aircraft they have on order.
More worrying for them is that the only 2007 aircraft I can find that they own had 1089 hours on it in December and now only has 1160, if that's an average accross the fleet then the writing would certainly be on the wall.
Good old G-INFO.