These aren't crazy cheap but meet all your other requirements: http://flutterwireless.com/ http://flutterwireless.com/ LoRa is a low power,low data rate modula

These aren't crazy cheap but meet all your other requirements: http://flutterwireless.com/ http://flutterwireless.com/ LoRa is a low power,low data rate modulation scheme that can transmit miles. Modules are starting to be available: http://www.microchip.com/design-centers/wireless-connectivity/motor-control/lora-technology http://www.microchip.com/design-centers/wireless-connectivit...