There is no better way to get started in robotics than playing with educational robot. The iRobot Create 2 is a programmable robot for educators and students. It helps you grasp the fundamentals of computer science and engineering. Create 2 can be connected to your laptop and hacked. You can attach sensors, electronics, grippers, and more.
Create 2 is Arduino and Raspberry Pi friendly. The kit ships with a cable that lets you connect your robot to your computer. Costs under $200 at this time.