Amen to that. $40 is nothing, much cheaper than what one of these "sights" probably cost. If you want to save the $40 you can bend the barrel in the fork of a tree or on the tailgate of a truck even. That's the best way to fix poi, just bend the barrel. Or if it's just high or low but fine left to right either file the sight down or build it up with some JB Weld. Simple. To me a shotgun is a pointing gun and a single bead is my preference for that application. In my experience those mid beads and rifle sights and all that fancy stuff just encourages aiming. Aiming is great for rifles but shotguns are better pointed.
And one other thing, back before screw chokes became popular, you didn't see all these point of impact problems in shotguns.