Re: buying a 147
If you are buying from a garage, it may be worth having a MOT carried out straight after as this will show any major problems with the car.
Check the oil and if it is very low make sure it is not using it excessively (Check out my thread on excessive oil consumption - it has been a real knightmare)!! Alfa's do not cope very well with cambelt breaks and if it has had one (which might require some investigating as I found), make sure the top and bottom ends were repaired correctly.
Check for unusal squeeks and rattles (this will often tell you if the cambelt was repaired correctly as the pulleys / variator should have been changed).
Other than that just the usual car checks really, brakes, coolant, the sniff test etc etc.
Without some experienced examination a bit of luck is always a factor when buying second hand!!
Go for it, when they work Alfa's are brilliant cars......