The cost will be over £1200 - £1500 per pair for the 7 inch which is on par with HID replacement headlamps, which is completly different from sticking HID bulbs in a halogen housing.
These lamps are most cost effective outside the military when used on either machinery subject to water & vibration or vehicles used at night or in a dark enviroment.
The PAR 36 / 4.5 inch we have our first set but are awaiting pricing, as the low and high beam are in seperate housings the technologies can be mixed to reduce cost, ie low beam LED and high beam incandescent.