EasyGimbal looks fine but pretty expensive; the Tarot, which is designed for quadcopters, can be fitted on pretty much anything, is of super high build quality and costs around $200:

http://www.helipal.com/tarot-t-2d-brushless-gimbal-for-gopro...

It's only 2D whereas the EasyGimbal is 3D but I don't think pan stabilization is much useful, except maybe when filming with the camera in hand. When attached to something (a bike, a motorbike, etc.) 2D stab is more than enough.