The best way to learn about robots is to build and program them. The ROBOTIS Mini DIY Robot Kit is an educational kit that gets you started in robotics. It has 16 Dynamixel XL-320 servos and 3D printable frames. You can control the robot from your smartphone. You can program its motion using R+ Task and R+ Motion software.
The robot has an expandable design, so you can add color sensor, LED modules, and other parts to enhance its capabilities. It is available for under $500 at this time.