Jim,
Rather than have to harvest proxies, here's a better alternative - and it's free.
The tool is called UltraSurf (ultrasurf.us) and it can basically be used to channel all search enquiries through a network of constantly refreshing free proxies. It's also used by millions of users for free internet privacy, and to get around firewall restrictions.
It first came to my attention as the developer for the Google Sweet Spot Tool (GSS) keyword analyser tool uses it, and it's flawless - I've never been blocked despite making zillions of enquiries.
With GSS, the developer generates the search queries in his app, and then runs them through Ultrasurf in the background. After 50 or so queries via one proxy set, the app then automatically gets another proxy and so on.
Perhaps worth a look - if you have any questions, get in touch and I'll do my best to help.
Cheers,
Chris