The ultraCage DSLR Event Handheld Rig, which includes the ultraCage, retails for $1,175. The ultraCage by itself runs $595.
High-end manufacturer of professional camera accessories, Chrosziel (www.chrosziel.com) has released two camera kits designed for the Nikon D800. The starter kit StudioRig Plus Kit Nikon D800 contains the 206-60S Studio Rig Plus that comes with gearwheel mod. 0.8, a flexible gear ring 206-30 for lenses with 60-90mm diameter, LWS lightweight support 401-421. The SR Plus + MB Kit Nikon D800 contains everything in the StudioRig Plus Kit and also contains Chrosziel's Mattebox 450-R20 with 410-80P Insertring Ø 110:80 mm (24mm tube), and DSLR handgrip 3300. Although Chrosziel gear is typically in a higher price bracket (pricing for the D800 kits TBD), high-quality German design and engineering is what you'll be rewarded with.
Achieving critical focus on a DSLR is possibly the hardest skill set to master. In working with the D800 and 5D Mark III's full-frame sensor, unless you're a professional focus puller, staying tack sharp on a moving subject on a long lens at an ƒ-stop lower than an ƒ/4 is extremely difficult (impossible if you're a novice filmmaker).
For focusing with Canon lenses, Zacuto is distributing a follow-focus device created by Okii Systems (www.okii.net) that will enable you to adjust focus remotely. By using Canon's USB protocol with a standard mini-B-to-A USB cable, the FC1 USB Focus Controller uses Canon's autofocus motor in lenses to control focus in the Live View mode. The focus knob of the FC1 has a number of buttons around its circumference that control other functions of the camera, including start/stop recording, digital zoom, saving focus points, and other camera adjustments. One really cool feature with the FC1 is the ability to set focus marks on two separate planes for quick rack focus moves. Once your marks are set, to perform a rack focus, you only need to alternate between two buttons. One drawback is that because of the autofocus mechanism within EF lenses, you might encounter some bumpy stair stepping, which isn't the most natural-looking focus pull. One button on the controller gives you three different settings of focus control. I found the second setting to be smooth, but if you need critical focus control within inches, the lowest or third step will give you the most control, almost as if you're pulling focus on a cinema-style lens with its large focus barrel. One thing to remember is that the autofocus motor noise will be heard during focus changes so it's best to use an external microphone and recorder while using the FC1.