I had a 924, was really cheap to run, didn't cost me anything out of the ordinary.. But like I said, you can use my dads mechanic (family friend) if you buy it...
Go drive the thing, the balance of them are amazing...... Took my 924 through mundaring weir road and it was just great.
edit: They are a 4cyl btw and parts from the UK are cheap and plentiful.
http://perth.gumtree.com.au/c-Cars-Vehicles-Motorbikes-Parts-cars-1982-Porche-for-a-only-3500-ono-W0QQAdIdZ307310865
924