Look for broken stuff
Nah, the km's are no indication of the cars true km's. Take it for a drive and make sure the g/box is ok, some are fairly s**thouse... But the owner can hide these problems with good oil. Interior trim is probably the best indication, if its worn well you know its done a fair few km's.
If you get a stock one, you know within 6 months you'll be upgrading the exhaust, airbox and a boost controller, so you can save a bit of money by getting a car with these things done. I think the best way is really to speak to the owner , if he says he spends the weekends waxing, servicing and other things you know this bloke will treat it like his baby, but if you buy from someone who says "Moite, I chop da rexs and da V8's all da time" you know its copped a caining.