A very good try and thanks for reporting back and your nice and valuable review of the subject that is contributory to the site.
These things are fun and for the price, you simply can't go wrong.
PS: One of the photographers in this site, has adapted his $ 2-3, Door Peephole Viewer into an add on fisheye lens for the camera, long before these companies sell similar idea in every shop, and successfully produced several good image, two of which are awarded as POTW (Picture of The Week) in the "Gallery" of this forum:
Link - 1
Link - 2