The idea has been floated a few other times. A now big time course builder told me that as a youngster working for another contractor, but still hoping to be an architect (looks silly now....) he had taken out an ad with the idea selling green details to clubs to save the cost of an architect. Just plug the plan you wanted into your site.
With CAD, it would be easy for any architect to put a collection of past green plans up for sale. With Google and CAD, it might not even be that hard to be an architect from a distance, and slightly tailor those plans to fit a site.
However, it would take one heck of a disclaimer to assure that if it failed for some reason, the Owner couldn't track you down to your little post office box and sue you for bad design.