Scott, do try and understand, most of my customers look for a bit more in their purchase than a bag of bolts, so I'm not relating to the broke dick mentality here, I have noticed your comments are coming from a cost perspective, not everyone is, plus you have to consider there are levels of distribution and different pricepoints, most porty guys prefer the service of a local dealer for help here and then, that cost something as well.
I would add that some of your numbers are just plain wrong, I know for a fact that to add autofill like it is plumbed on the GG-M5 complete, cost quite a bit more than you suggest, keep in mind some folks demand more than a do it your self hole drilled in the freshy and a floatvalve installed, just like some folks demand better than Stanley or Rug Dr. when they seek out carpet cleaning.
and....to answer some earlier misinformation, a GG checkvalve jet extender has TWICE the checking pressure of the standard industry checkvalve, but it really doesn't matter, cause Uncle MeAt is dead on, high heat changes everything.