Certainly a well maintained one, flown by an individual of above average skill levels, is a capable aeroplane.
The Aerostar needs a different mindset than most other light twins. It is a significantly more sophisticated aeroplane and needs to be flown in a more disciplined, check list driven manner. A Baron or Seneca you can still "kick the tyres and light the fires". Only the foolhardy will do this with an Aerostar.
I believe it was designed with the intent of developing into a jet. Many of its systems are different than other light twins and they require understanding. The fuel system is a good case in point. Its very simple, but its different and you need to understand how - which funnily enough can be achieved by reading the POH.
I think you could fly a Baron / 310 / Seneca with a basic twin rating and get away with it. I'm not sure that is the same case for an Aerostar. The Aerostar is just an aeroplane and it was designed for mere mortals to fly. You just need to pay attention and not assume its a scaled up Bonanza or Cherokee.
In part its more expensive because its bigger with more complex systems and some stuff is tightly packaged and hard to get to. In part its expensive because most owners follow the manufacturer service schedule and not CASA part 5 and in part its expensive because Australia just seems to do that. There are many things that are inexplicably more expensive here than the US.
A pressurised Aerostar cruising in the flight levels is an awesome thing.