There are buyer's guides at AWS
, other than the stuff one should look for in any second hand car, pay attention to...
Suspension knocking/creaking, a particular Alfa weakness, mind you if it isn't creaking/knocking now chances are it soon will be.
Make sure it starts easily, moves off, accellerates, drives and stops in straight line
Electrics, make sure everything works, if it's got heated seats make sure they work, the switches have a habit of melting.
Look for proof of a cambelt change. The book states 72K miles, however there are reports of the waterpump letting go. Wisdom advises belts, tensioner and waterpump at 48K miles or 4 years.
The JTD engine is bulletproof, I've heard of no reports of cam, crank, gasket, piston, valve, bearing problems - but you'd know that.
The EGR.... you know all about that.
Cosmetic stuff, alloy kerbing, stone chips, cabin scratches
Annoying stuff, cabin rattles that sort of thing
Try the air-con
Look for a toolkit and condition of the spare.
Have a look at the skirts/sills near the wheels, these can be crushed by careless mechanics/tyre fitters
Look at the bonnet where the driver's winsdcreen wiper would be at its maximum travel, it has a habit of catching and damaging the arm and bonnet.
The exterior door handle hinge is weak, check both doors.
Check paperwork, 2 keys and service history.
That looks like quite a list but it's not too much more than one would look for on any second hand car, and a lot less than many. If the suspension wasn't so weak this would be a very quiet forum.
All the best