If it's line-of-site, why wait? There are existing point-to-point wireless bridges. They aren't terribly expensive (~$1,000) and they'll easily bridge several miles at 100Mbps full duplex. A quick Google revealed this possibility: »
www.gridconnect.comI'll bet more searching would find something even cheaper.
If you are technically inclined, you could also get by on the cheap by using high power 802.11 devices coupled with high-gain, directional antennas. Check out this site for high power equipment: »
www.engeniustech.com