This one is interesting. A Cube rig that has a hoop over the camera mount. Use the hoop to set start and stop marks and you basically have a low end follow focus with easy to set start and stop points. Square camera cages are generally a good thing and normally give you plenty of mounting options. The price is a little high at $249, but a rig and follow focus will usually cost you more then that, and the combination could end up being a good deal for some.

The video is topped with a little bit of cheese, but over all it seems like a good idea. You can find out more by visiting the ARCHRIG website. I wonder if mounting gear on top of this rig will get in the way of the follow focus design. Might need to make it a little bit taller.