So you are looking to get your hands on an advanced hexapod robot kit with open source software? The PhantomX AX Metal Hexapod Mark III from Interbotix Labs has you covered. It has 3 DOF legs, an ArbotiX Robocontroller with is compatible with Arduino, and rugged full metal frame construction.
You can control the robot wirelessly via PC or joystick. The MKIII robot is driven by AX series DYNAMIXEL robot servos. You can find it here.