Hmmm, ok, that is good to know. I did as dwanthny did of creating a resources\images subfolder, moving all the stip_* images in there, removed them from my other directories (Program Files and source code), restarted Calibre and the Search the Internet plugin worked fine. So no coding changes needed.
However before I update any instructions for gui plugins that still leaves my suggestion about installing a plugin. I think it would be nice if when you install it checks the zip for any images and if present puts them in this resources\images folder for you, to remove the manual steps.
Does such functionality exist already, or should I create a ticket?