You cannot deny that GW are widening the scope of releases among the 40K spin off games, even giving these little factions rules but, alas, no full 40K army yet.
As far as Cultists go, there are now the basic snap-fit models, the Renegade Guardsmen and Traitor Command (Commissar and Ogryn) from Blackstone Fortress and the latest flavour, the Firebrand and his Cultists.
I have two sets of the Cultists lines up, one from Escalation and the other set from their solo release. Nice models and like the drum magazine autoguns.
I bought a set of the Servants Of The Abyss to include some more renegade Guard. Using the heavy stubber from my second Cultists set, I have converted the flamer Guardsmen to pack some more firepower.
I'm tempted to got for the yellow colour scheme that I used on one of the two sets painted previously.