I don't see Ghosts I-IV Ultra-DE and Cargo In The Blood as comparable really. They happen to have the same price, but one is a NIN release and one is a book of art by Russell Mills. The NIN association definitely attracts the larger NIN audience who might be fans of Mills or the work, but I don't think many people will buy it solely because of its association with NIN (at least, I don't think that's the main audience).
How many sales to similar books of art* sell anyway?
(* And what's the proper name for this sort of release? I don't want to say "art book" because that's
a different thing in my mind.)