Microwave+Experiment

http://www.tomshardware.com/forum/39902-43-long-range-miles-directional-wifi-signal-boosting

You could install your own point-to-point microwave specifically designed for what you want to do.

A pair of Ubiquiti airMAX Nanobridge M units will do what you want. They can use TDMA in a point-to-point situation with an advertised range of 20 km. I use 4 of these and my longest hop is 41 km (26 miles) with perfect results. I use the larger 16 inch dishes. In the TDMA mode, there is near-zero latency and nobody is going to leech off of you either.

They are PoE powered (injector is included) and setup is performed using a built-in webpage type interface similar to any router. This is carrier-class equipment.

Cost: about U.S. $80.00 each on Ebay. Search for "Nanobridge M."

The Ubiquiti site is **__HERE.__** Click on the Nanobridge M picture-link under the words "Airmax antennas."

They are available in 4 versions: 900 Mhz, 2.4 Ghz, 3 Ghz, and 5 Ghz. and no license is required in most countries.

It is also possible to use just one unit as a standard Wifi receiver, AP, or bridge.