A thread over at SearchEngineWatch Forums is currently in the process of discussing why one product result ranks in the Google main results, while other sites do not. There are dozens of theories as to why, one such theory is that they select a low, middle, and high range for the top 3. When I say low middle and high I mean price range. They pick the "best match" from these 3 ranges and display them in order of lowest price to highest price.
However, there is nothing like doing your own testing and data collection and analysis. Therefore, I have had one of my developers build a Froogle data collection tool. We will be storing results for requested queries and then I will be conducting statistical analysis with SAS and Excel to find patterns.
I will not be allowing the automated submission of keywords to be tested. If you would like your keywords to be tested, please submit them at the SearchEngineWatch Forums Thread and I will be happy to run tests with your keyword requests or you can add a comment to this entry.