Seconding what quietrush says, you could pay way too much for a Focus XR5 (exactly the same mechanically as a C30 T5 with a yobbo tune), a Focus RS (with a crappy weak Ecoboost 4 cylinder) or Mazda MPS (with a similar and fragile turbo 4). The C30 is a much more refined vehicle to live with - they're all based on the Volvo P1 platform so have the same brakes, suspension, steering etc... and has beautiful leather seats and much more style (objectively). The icing on the cake is the turbo 5 cylinder thrum which only the Focus XR5 can equal (because it's the same !) and the Volvo seems to be around half the price. The 5 cylinder engine sounds like a grown-up Subaru WRX on full throttle.
That said, the 2 main reason these cars get cheap very quickly is the cooling system (particularly coolant reservoir and radiator / heater hoses) and the timing belt.
Coolant reservoir: they crack. If the reservoir looks at all yellow or brown, just replace it. They're stupidly cheap. Volvo have a low level sensor on the windscreen washer water but not on the coolant reservoir. (We got our free S40 AWD because of the cooked engine)
Timing belt: Never seen one of these fail...however the timing belt tensioner is the "weak link" - I don't think they're a problem if serviced by the book, but you need to change the tensioner and idler pulleys with the belt. Only change the water pump every second belt change, and only with a genuine Aisin pump. (The cooked S40 was due to a failed cheap water pump which was changed with the timing belt at 100,000km, and should have been left alone...) Our recent C30 T5 purchase was almost ruined - because of no service record at 200,000km I changed the timing belt (full kit) to find that the tensioner had been broken on last installation and the belt was at risk of jumping timing.
They're the only two areas I'd really have any concern about in Australia. Our C30 has almost no brake pads left, but the brakes are perfectly fine unless you're doing serious track days.