Recently I was Google-ing for laptop screen cleaners. Of course I was searching for the best price. When my search results came up, I sorted them by lowest price. The first 3 results with the lowest price indicated Free Shipping. Perfect!
When I accessed each search result, each one of them was charging $9.95 for shipping!
So, if you come across a similar situation with your Google Product Search and would like to complain to Google about it, go here: http://www.google.com/support/merchants/bin/request.py?contact_type=policy