In the arduino robotics book written by John-David warren there is a segbot project on which I am working.
I don't know If this can help but I bought 2 second hand wheel chair wheels and motors from a local store and took the brakes off.
For the motor controller I ordered a sabertooth 2x25 from www.dimensionengineering.com.
I could not find a 6 dof Imu (where did you buy it?) so I ordered an accelerometer and a gyroscope from the arduino store (tinker) together with an arduino UNO.
These products have not yet been delivered so I have not been able to try them out....yet.