Robotic hand is one of most important parts in robot equipment. This is main manipulator that interacts with outside world. Complex robotic hand may be very expensive part that may be hardly achievable by hobbyist. Anyway you are always free to experiment and find new ways of reducing cost while making it worth using. Aaron Thomen have been experimenting with interesting robotic Arm solution controlled by Arduino.
As you can see. Few smart approaches makes it really responsive and realistic enough. It is basically made using servo motors and spring-loaded fingers. Fingers are maid of bicycle chains that have many joints and are really flexible. Servo motors activate finger by pulling strings. It is able to pick small objects pretty well what makes it great candidate in many awesome projects. So this is an example of how complex things can be done simple way.