Fuzz,
The real problem is that you're looking at a 10-17 year old car. If it's been maintained with 10,000km service intervals (15,000 is recommended but just too long if the garage uses cheap (discount...) oil) and whoever serviced it knew what to look for and kept on top of things like coolant reservoirs... then you could snag a peach which will run for another 300,000km with regular scheduled services. However you're more likely to find a car with another kind of "history"...
Our (free) S40 T5 AWD, apart from having a butchered air cleaner box (collapsed engine mount meant the monkey didn't know how to remove it), and a missing strut spacer on the left. When we got it running again, it chewed through tyres at an alarming rate and 3 alignment places couldn't sort it out. Even replacing the spacer didn't help. Eventually we worked out that it had hit a pothole / bump at speed in its past and the left lower control arm had a slight bend to it. Cheap fix (Ford replacement) and tyre wear is normal now.
The C30 T5 manual was an expensive car from a Sydney dealer with unknown history and 200,000 country kms. Apart from the A/C fault, timing belt time bomb and horrible wobble at speed (dealer fitted Dong Feng tyres...grrr...) and the rear washer spraying into the headliner (...grrr...), it's been a delight to own. It's effectively a luxurious and stylish Ford Focus RS for half the money. Are Mazda 3 and Ford Focus models unreliable as first cars ? No less so than the Volvo platform, but they too need regular attention. Most modern cars do. Look at the number of newer Kias and Hyundais needing replacement engines, usually because they tend to burn oil and nobody checks the oil level any more.
We sold our older 2003 S40 to a friend with 120,000km on it. We'd bought it near new with 30,000km (ie after only the second factory service) and it was a real gem. However our friend isn't a car guy and didn't know what to do when the coolant temp sensor failed, the cam phasers started spraying oil...as a "cheap car" he's not enjoyed the Volvo experience...and yes his other car is a Toyota.
Do you need to be a Volvo fanatic to own a C30/S40 ? Most first or second owners weren't. Do you need to be realistic about the level of care and attention (either time or money) any car should get ? Of course. The real problem is that these cars have had probably 2 careful owners when they were worth something, but they were always the "cheap Volvos" and the third, fourth and later owners were probably trying to "economise" on expenses. Finding a good one for the right money is the key I think.