David,

Look out for leaking head gasket and that it starts ok when cold, other than
that these engines are fairly bullet-proof.
Make sure the window demister works ok, and there is no damp anywhere in the
vehicle.
If it has power steering, check for leaks.
Listen for loud whining noise from the alternator (there shouldn't be one)
check all electrics.
If it has ABS, take it to a stretch of gravel or very wet slipy road and
test it.
Check the condition of the tyres and exhaust (Good bargaining points)

At that price I suspect the cambelt is due, along with a good service and
seeing too.
Possibly the brakes will need checking too.
(Unless you know the guy very well, do not take his word on the cambelt
'just been done mate')
In my experience, if somebody says the cambelt was done not so long back, it
means 4-6 years ago.

They are reasonable cars at this price bracket.

Andy