HP Video sent me a link to this little video demo for their HDSLR wireless transmitter. They claim a 500’ to 700’ range for transmission. The transmitter can be powered via a four pin XLR 12V power supply or via power tap connector. The receiver/monitor can be powered by either sony mount batteries or via four pin XLR power to 12V power supply. The wireless system includes a monitor with built in receiver, transmitter, power supply cable and two antennas. Retail price for the system is around $2800 US.
Check it out here.