I've got a used (but in great shape) Arri light-weight 15mm follow focus. It's originally designed for the 16mm SR light-weight rods, but should work fine with any standard-geared lenses using a 15mm LW system. This is no where near as cool as Arri's current LW and Mini FF systems, but it's also not priced at the $1800+ those go for. I'm asking $500.
I've attached some pics. First come, first serve.