Take a look at the buying guide on www.gtvv6.com.which is for the 3 litre V6,but will cover most of the issues.
The main things to check are:
1)Cambelt: If the car has high mileage,has the cambelt and varaitors been changed?
2)Rear suspension:bushes on rear wishbones wear.Cheap to replace,but can cause wear on rear subframe if left,and then expensive to fix.
3)Ask the owner how often he checked the oil.The 2.o TS can use a lot of oil and the uninitiated let them run low.
Hope this helps.
Some days you`re the statue and some days you`re the pigeon
If you get a whirring noise when depressing the clutch and not when the clutch is released then it is going to be the clutch release bearing. Basically it means you clutch is on its way out and will need replacing not cheap I think an Alfa dealer will quote you £800. You'll probably notice your clutch is getting quite heavy.