I think this is the biggest mistake first-time buyers make on Themeforest.
There was an old post about this problem; http://themeforest.net/forums/thread/difference-between-a-theme-and-a-template/66047
I think adding an additional warning message or a video to the first-time buyer purchase screen would be a good idea. I believe that a video like the following will prevent first-time buyers from buying a wrong product;
What do you think guys…?