Perhaps they should be more honest that this is temporary, "early access" pricing. Perhaps they should say "The Fifth Witness: Electronic Early Access Edition, $15", and promise "The Fifth Witness: Electronic Mass Market Edition, $7". After all, early access is a reasonable thing to charge money for.
I also seem to recall reading elsewhere that authors get a much bigger cut of hardback sales than they do of mass market paperback sales. Perhaps this should be advertised more prominently?