A quick Google check shows the price of a P68 as being around Euros 670,000 each but to that you need add zillions for the required role fit, an MX-10 downlink, radio fit etc is no cheaper just because it is on a f/w.
The prices being quoted before are probably the cost of the Airborne Technologies trial lease. As a trial it does not matter what fuel is used. An MX-10 costs a tad more than £145,000!
If they do not go for a turbine f/w they may find cost even more and may depend on airport fuel farms and bowsers.
Just been to the new unit at Hurn and they are sub 24 hour as is the airfield. The plan is that the 24 hour NPAS helicopters can land when it is all closed up and serve themselves from the fuel at the unit...... that means that the f/w fleet will not be as flexible and may not be seen as 24/7 as needing to be able to get to fuel.