Personally, I'd rather have a 172 with average miles (or just below) than one that has only covered 10-20k tbh. Cars that are used daily and maintained as they should be, are more reliable than cars that are sat about for long periods of time.
I managed to get a black 2002 172, which the only defect visually are some kerb marks on the wheels, which had done 40k for £5800 (from dealer).
People seem to get hung up on the mileage, and think a 20k car is better than 40-50k, but it depends what it was used for. Mine was used for motorway driving. I'd take that over a 20k car used for 5 mile trips anyday!!