my cambelt on mine snapped at 6yrs old and 145k miles (original belt)
high millage ones are fine infact i prefer them as you get a good bargain, check for regular service history and the one thing that likely wont be done that i recomend is changing the gearbox oil, coolant and brake fluid as no one really bothers.
service it well with good plugs, decent oil and genuine oil filters and it will run for atleast 200k if you dont abuse it.
look out for leaking rear dampers (check all dampers though on higher millage ones especially) snapped coil springs, worn out ARB drop links, driveshafts and gaitors and listen for noise wheel bearings, thats about your lot that will go wrong to be honest, theres probably 100 other wee silly niggles but thats your main ones. the good things about these cars is they are actually pretty reliable the things that go wrong generally go wrong with all of them! lol
EDIT: also rough, lumpy idle or trying to stall when slowing down at rounabouts is another common fault on them that can be caused by a few things usually coil pack or the wiring on the back of the engine, if its coil pack then use it as a bargaining point, if its the wiring then walk away unless you know what ur doing lol