Yes, this is turning into something that is substantially more difficult than it should be. It would appear that all the parts exist, and are in no way restricted, but there is no easy avenue to purchase them through the civvy route (AIDU I believe don't sell them.) Surely something that would be useful to a lot of civvy pilots (Air Ambulance in particular). Why, oh why, is this product not easily available?
My next port of call is OS themselves...