Push down on the front fender and see what happens. The car should bounce/oscillate 2-3 times slowing down and moving a shorter distance each time. If the car keeps bouncing more than 5 or 6 times (or doesn't stop at all) then your shocks are probably bad.
Remove one shock (or all the ones that seem bad), take it apart from the spring and compress it by hand. If there's no resistance and it doesn't re-extend itself, then you know it's bad.
Try that before you go buying replacements.