You could use a common video camera. It won't be as accurate as a true high speed camera, but it should suffice for experimental purposes. Mount the camera in front of the pendulum at the height of the pendulum at rest. Put a screen behind the pendulum with a pattern of squares on it. Place the screen the same distance from the pendulum as the camera (makes calculating height and swing easier). Even better, two cameras and two screens at 90 deg. from each other.