If money is no object... Motion Sim or Force Dynamics
http://www.motion-sim.cz/new/?page=h...icle=7&menu=31
http://www.force-dynamics.com/
Force Dynamics is the absolute best of the best.
Roughly $28-85K
I've used the Force Dynamics 401 before at an entertainment show. It is absolutely amazing. They had the settings turned down a bit low since it was public but it was able to transition from smooth to absolutely spine breaking violent seamlessly. Got off that thing and felt like I forgot how to walk.