I just picked up an is300 three weeks ago here in Victoria too.  Where are you getting yours?
 
I can tell you a few things to have the service inspector look for in detail, or you can ask who ever you are buying it from if the following has been done:
 - timing belt, water pump, and seals at the front of the engine.
 - spark plugs and valve cover gaskets should be done.
 - front suspension refresh.  The lower control/castor arm 
bushings only last about 5 years, allowing excessive toe out and massive 
inner tire wear and shudder under braking.  Ask if these were done.
 - also check ball joints, upper and lower, there was an 
issue some people were having causing their lower ball joints to let go while driving. 
 - also have them check the radiator and hoses