I found a very interesting semi DIY wireless follow focus here: http://www.ebay.com/itm/Wireless-Follow-Focus-Wireless-Servo-Controller-with-Limit-Position-Memory-/261698066026?pt=LH_DefaultDomain_0&hash=item3cee6b966a
There's also something what looks like enclosed version: http://www.ebay.com/itm/Wireless-follow-focus-for-DSLR-rail-System-Transmitter-Remote-Controller-/381146236540?pt=LH_DefaultDomain_0&hash=item58be16067c but without Max range and memory points
This is slightly cheaper finished one
Biggest issue with them is usually drive used. Can be very weak and noisy.
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