I just wrote a script that queried the database and then outputted a tab deliminated table of all of the data. You can see the format of what it needs to be here: http://base.google.com/support/bin/a...er=58083&hl=en
Our particular feed it located here: http://interwestsafety.com/googlebase.php
You can have your script look at a flag in the database and not show products that you don't want to show up. Also, products with a price of $0.00 are already excluded by Google.