I was given a Weye-Feye XS unit to test out for an electronics importer here in Australia, and I have found it to be great to use.
The unit plugs into your camera (any DSLR you have) through the USB port in the camera, and you download an app on your I-Phone or Android device, and you have full live view on your phone or pad, without wires or cables between you and the camera.
The live view is very good, and the delay is only around 0.2 of a second. You can also magnify the live view in various steps and return to normal viewing too (handy for spot focussing).
You can focus the camera by just touching the spot on the screen you wish to focus on, and you have full control of aperture, shutter etc, and can even switch the camera to video mode and take videos at will.
The battery of the control unit lasts for around 6-8 hours and is charged via a USB port.
Any photos you take are downloaded onto your mobile device within seconds of taking the picture.
It should retail for around $100 or so.
You can see the device at www.weye-feye.com
I have no affiliation with this company.
Interesting, any idea in Australia where it's available from ??
I note the Weye Feye ($249) is not compatible with the 1Dx but it is compatible with the 6D/5DMK III
The Weye Feye S ($100) may have more compatibility, but the web site lists this cheaper version as "Not in stock".
I can find no where on their website to download actual upgrade files, though there is a manual that shows how to upgrade the unit, just no actual file or area where it could be.
Coupled with the iPad Mini Retina this might well be a sensible reasonably priced alternative to say the Marshall 70MD which I've been contemplating for a little while now.
Unfortunately the website looks like it was put together by an amateur, missing links, no support info.