It can be cost effective though. My old Police Air Unit based on the old Filton Airfield, (now closed and sold for development) were given their marching orders by the new developers, as were the Great Western Air Ambulance unit, mentioned by PA News above. They were both forced to look for a new site, but quickly realised that they both operated EC135's, both required similar maintenance and administrative support etc and all the other add on's that units need, so agreed to form a combined unit. Still entirely separate from each other but combining premises and everything else apart from operational matters.
Now that seems a good way of giving a good bank for the buck to me!
Tigerfish