The 2WD and 4WD Robot Platforms from Rapid give you the opportunity to build a simple robot at a bargain price. They're based around an anodised aluminium chassis which is pre-cut for servos. The chassis also has a useful set of mounting holes and slots for additional hardware such as a microcontroller or sensors. These platforms are compatible with any microcontroller such as the Arduino, OrangePip, PICAXE, Genie and others, as servos do not require additional motor drivers.
All the parts for the platform are included in the box: 1 x anodised aluminium chassis, screws and nuts, just add your own microcontroller. The 2WD platform also includes 2 x servos, 2 x wheels with tyres, and 1 x castor. The 4WD platform also includes 4 x servos, and 4 x wheels with tyres.