Good documented service records are very important. Annual valve adjustments along with new fuel filters are a must. The fuel tank screen should be cleaned at least every 2-3 years depending on the quality of diesel fuel in your area. There are also areas that are prone to rust:

Hood hinge pockets
Battery tray
Front and Rear window lower channels
Floors (remove the carpets and inspect the floors)
Jacking points
Bottom of doors
Sunroof (if so equipped) channels

Mechanically with this number of miles the vacuum pump should have been replaced and the transmission should have been serviced every 40,000 miles. Cracks in the dash (or a lack thereof) will add or subtract from the value of the car. Crack free replacement dashes are very rare. Driveline flex joints should have been inspected an/or replaced. All accessories including the cruise control, wipers, radio and radio antenna along with the rear window defroster should be fully functional. All vacuum operated door/trunk/fuel door should be fully functional. The ignition switch assembly is subject to wear and may have been replaced.

I am sure others will add to this list. If these items check out and the car is cosmetically sound, $5,000 (AUD) sounds like a fair price.