My policy has long been to publish separate vignettes, then "the full trilogy," then, usually a paperback version of the trils.
The vignettes would be $2.99--other prices extrapolated from there.
It's been made clear to me that this was too much for too little.
So . . . I've taken down everything but the "full trilogies" (and a few anthologies) and re-priced the full books at $2.99 (Now Perma-70% Off!).
Not sure how long this will take to trickle through 'Zon (I think you can't take something down until the KDP prison term expires).
Cheers!
Joy