can't go wrong at £200 really, just do the standard 2nd hand car checks.
Smoke colour is NOT blue.
Dip you finger in the water to see if its normal and not oily or mixed with white stuff
see how many clicks it takes for the handbrake to reach maxium (should be 3)
Take it for a test drive and see if it moves with the handbrake up
See if it brakes evenly when you slam on the brakes at 40MPH (find a clear safe place to do this)
make sure all the gears engage properly
Make sure the on releasing the clutch the biting point aint really really high
see if you can move the car on a flat surface with the clutch alone. a strong clutch should be able to and this is a good thing.
Make sure that when you let go of the wheel it drives fairly straight and that you do not have to hold the wheel at an angle to make the car drive straight
check body for rust, different colour paint, knocks and dents blah blah.
check suspension; bounce the car a few times and let go and see how long it takes to stop bouncing.
try and look under the car to make sure nothings bent at the front end as this may mean the cars been in a large accident and may give you trouble for life.
make sure the car was cold when you went to see it or go to see it again and that it starts from cold easily.
make sure the engine hasn't been steam cleaned otherwise chances are you got an oil leak.... but this is common with Fiats and is usually just a case of replacing the rubber seal.
if its got central locking make sure all the doors lock and open or you'll need a new central locking motor. £5 at scrap yard, £50 at dealers.
Good luck mate