Those prongs on the clips are poked thru the run channel and bent over slightly to secure them. At least that's the way they were when I removed the old ratty run channel from my doors. I have a couple of those on order (most were salvageable) and will attempt to install them that way when I get to that point. Although looking at your pics, and inspecting the run channel support that screws into the door, it appears I'm still missing the ones with the hook on them.
And yes those little steel bits are expensive!