There is no better way to learn robotics than building and programming your own. This Yahboom Raspberry Pi Tank Robot is worth a look. It has a 480p camera that supports real-time transmission. It can be programmed by C and Python. The robot can handle inclines up to 60 degrees and avoid obstacles.
This tank robot can be controlled by an Android device. It ships with ultrasonic sensor, battery, Bluetooth module, servos and everything you need to get started.