It depends a lot on how the car has been looked after - with regular oil changes the engines can last just about for ever. Other things are more important than mileage - it the engine smooth at idle and starts and drives OK then the engine is good.
Mileage by itself is not really high on my list of things to look for. Body, chassis, interior and mechanical condition are higher on my list, and it's nice if there are some new bits like dampers and radiator.