I was once interested in a Black Daylily as well. But you know what I found when I got some dark ones?
They got lost in the garden. Unless they were up against something light to show the contrast.
Hanson's EXON VALDEZ is dark dark dark
BLACK ICE is a thin dark one.
Both are darker than what they show in the photos.
There is another of Curt's that is blackish too. Juli? I can't seem to think of the name at the moment.