The claimed subject matter relates to a computer-implemented architecture that can provide a non-invasive comparative shopping tool, such as a browser plug-in. For example, the plug-in can determine whether a web user is currently visiting a purchase page, thus indicating that the web user is likely to be interested in purchasing items online. Upon making this determination, the plug-in can display a non-invasive listing (that can be quickly and conveniently dismissed) of comparable items at favorable prices (or with favorable features, etc.) that are available for purchase at other web sites. In addition, the plug-in can communicate with a data store, e.g., by way of the web, in order to help make various determination as well as to receive the listing of comparable items.