Eric,
Indeed you can, but buying the aircraft is a small part of the Through Life Costs. Modifying them, testing them and certifying them for anything other than benign theatres will cost an awful lot of money. If I were still in the mil, looking at the recent safety record of the 225 family (flying straight & level) I'm not sure I'd want to stick a whole load of DAS, armour and guns on it then fly tactically at low level.....