I think that, no matter what route you take, its difficult to pull much over 1g, and therefore you wont get as realistic as real life. I dont know for sure, but I am guessing that force dynamics tries to compensate for this by giving you a wide range of movement. But saying you dont like the way it looks without having actually tried one? Im not sure that's the right approach to making a motion rig. Considering its motion were talking about here, itd be wise to try to test some actual motion through feel rather than eyesight alone.
Im not saying that force dynamics is great, bad or indifferent, simply because Ive never tried it. but one things for sure, i would sure as hell like to try one.
Now, onto a cheaper method? this guy built one out of pvc pipe and windshield wiper motors. browse through the site, hes got alot of how-to's, and videos. THough he built it mainly for flight sim, he also has vids running LFS with a wheel on it.
http://www.motionflightsim.eu.tp/