I'll second that on http://cantenna.com - Jason and the team there have been providing an excellent source of these antenna's for almost a decade. (I can vouch for the integrity of the product because we were one of the biggest consumers of their product in the day on my site http://netstumbler.com)

I assume that the interest in this is back because of Marius Milner the Google employee who built the Netstumbler software http://www.netstumbler.com / http://stumbler.net is the suspected engineer who wrote the Google software that has been in the news about the mapping of access points by Google streets cars.