I used to sell flight simulators and for a Full Flight "Level D" they were well over £10m back in the late 1990's.
£10m would be the cost of the base simulator and motion system to which you would need to add:
Aircraft hardware and computors - everything the pilot can touch is the same as the actual aircraft
A flight data pack supplied by the aircraft manufacturer to provide the aircraft operational and flying characteristics. These were typically a couple of millon £ or so
A visual system for the out of cockpit view. These provide a computer simulated view of the airports and surrounding areas.
Level D allows zero flight time trainang and type approval so a pilot could complete all his trianing on the sim and the first time they flew the actual aircraft could be on an operational passenger flight. Indeed, there are now many aircraft types where a pilot has to quailify on a sim as it's too dangerous to train for certain emergencies on a real aircraft.
They are amazing bits of kit and one of the best "toys" to play with
