I have a 3 foot Kessler Pocket Dolly Basic available for $380 O.B.O. I purchased it a couple years ago for around $600 from Vistek. ca.
http://www.vistek.ca/store/ProVideoCameraStabilization/262801/kessler-pocket-dolly-v2-basic-no-quick-release.aspx.
However this one comes with the brake and the puck that permits you to put your tripod head onto it, and likewise the initial box that it can be found in.
It functions terrific, smooth and good, I actually haven't used everything that much given that I purchased it because it was a little as well much to bring around, and I required 2 tripods to use it.