148,000 Miles on an alfa??? that must be a new world record!!!
aviod imo unless you like fixing it more than driving it
I've read about them being higher!
This car sounds like the check list for buying an unreliable car
-Alfa - check
-High mileage -check
-Diesel - check
Part of me thinks its so much the stereotypical unreliable car, Sod's law will dictate it turns out OK!
However, being more subjective about it, the 1.9 is the same engine going into fiat, vauxhall, Saab amongst others. These aren't unreliable engines, the EGR is the biggest worry here but they're not expensive. In the case of Saab, it's a ~200 quid part from the dealer but buy one for a vectra from a vauxhall dealer (same part) and its more like 80.
At this mileage the clutch has almost certainly already been done - make sure the documentation has this and a cambelt/water pump recently. The turbo, if its not noisy or burning oil then it wouldn't worry me too much. Suspension, brakes and the like are quite cheap on the 147.
Electrics and bits of interior trim dropping off are probably the biggest issue so make sure everything works and check for bodged wiring under the bonnet.
Lets be honest, it's not going to be a completely worry free car but its not as much of a guaranteed instant explosion as some would say. The car has got to 150k miles hasn't it? You could probably pay 800 for it and get something that looks much nicer than other hatchbacks, is good on fuel and enjoyable to drive.