There is at least one AH-1S operating as a private aircraft in Oregon. In fact, Northwest Helicopters has one for sale. By FAA regulation once FAA registered it can only be put into either Experimental-Exhibition ( or some other category in Experimental) or Type Certificated in Restricted if the owner wants to get thoroughly involved in FAA bureaucracy. If a Cobra is owned or loaned to a public agency it is not required to be either FAA registered or even have an Airworthiness Certificate. Some agencies have internal requirements to do so, and most agencies will get heavily involved in ICAP or other program to insure the aircraft is safe.
There are a lot of surplus aircraft in public agencies. Oklahoma has an OH-58 as well as a Beech Queen Air (U-8) in their stable. Georgia has a UH-1H for fire fighting and Border Patrol has 6-7 UH-1H's.