Here's a little trick that should help 'narrow' what people are looking for online on a broder scale.
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and type in search terms such as 'buy' or 'purchase' whatever you can think of that people may search for. This will search out the related keywords that contain the word you entered. It will tell you how many searches were done last month and the full phrase used.
I believe it gets results from the yahoo network consisting of other networks such as msn.