E.g. a Yagi from B&B - http://www.bb-elec.c...l=3&TrailType=Top - $125 for 12.5 dB of gain at 2.4 GHz (though the datasheet says 15 dB of gain).
Cringely (at his old PBS haunts) talked about getting wireless service in the boonies and building his own pair of Yagis for about $100. - http://www.pbs.org/c...20207_000721.html (Note that the links to the sources are on the Right now - the "Links of the Week" in the text is broken.)
More is in his earlier article as well - http://www.pbs.org/c...10628_000421.html
HTH! Have fun.
Cheers,
Scott.