Not sure what went wrong here. I certainly don't see where anyone sells even the 3-cnt for anywhere near $4.. I can only speculate that the offer was for $4 at some point, and when they reduced it to $2, they forgot to remove the '50% OFF' designator.
I have a few of the Lemi-Shine ones that I have not used. You are suggesting just using non-chlorine bleach in an empty load instead, correct?
I have a top-loader and I find I avoid/mitigate the mildewy smell if I just leave the lid up.
But I still should clean it