Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.
$3,500 is pretty cheap for a VX here in WA but there are a few basic things to look for.
Let the engine run for 2 minutes or so and open the radiator cap (slowly) to see if pressure has built up. Check all fluid colours and levels
Make sure the ABS unit is plugged in, people tend to unplug them to stop error lights from coming up.
Make sure the car drives and runs straight and everything works (right down to rear electric window switches and cruise control)
Look up and make sure roof lining isn't sagged lol
If you need any parts ect just give me a call/message I have heaps of VX gear. They're good for over 400,000km if you look after the motors. 240,000km is still young.