Auto-detecting product data feeds for an arbitrary E-Commerce site?

Question

Hey all!

My web app needs to access an arbitrary E-Commerce store and determine whether or not it has a product data feed (i.e. a Google Base feed; an RSS/ATOM feed of all products in the store). Also, I need to extract the location of this feed.

The best solution I can think of so far is to maintain a comprehensive list of known locations of these feeds for given E-Commerce platforms and check them one by one for the site, crossing them off the list as they come back 404.

Two questions:

1. Can you think of a better approach?
2. How would I go about generating this list of known product data feed locations? In my experience, they are generally not made public (unlike blog RSS feeds).

Thanks so much! :)

-Rich