I'm curious. What are the criteria and/or parameters for listing a product as a Top Seller? Must it be a Paizo product? Are sales totaled for the week? month? year? all time?
The Top Sellers feed in the sidebar is supposed to be dependent on which area of the paizo.com store you're currently viewing. For instance, if you're on the frontpage, it's based on the entire store, but if you're browsing Pathfinder Society Scenarios, it will give you the top selling scenarios.
It factors in recent sales. (It's been several years since I thought about it, so I can't tell you the exact time off the top of my head, but it's on the order of a couple weeks.)