Are there any airports or hospitals nearby? It shouldn't matter if you are using the 2.4Ghz range, but there are upper power requirements that the FCC has. You will most likely need 2 directional yagi antennas. It will probably cost around $500 for the equiptment.

You should go to www.slashdot.org and search for this topic. A lot of the people there have setup this kind of thing. There is one city in Austrailia that has a bunch of people connected this way.

This is very possible if you do your research and have the cash.