How about using the Binder or the Warlock as the basis of the Cultist? Basically, each guy gets one or two spell-like abilities that he can use all day, but they otherwise kinda suck.
Here's one based off the Shadowcaster:
Fear Cultist -- HD 1d8
BAB: 3/4
Good Saves: Will
Skills -- 4+Int / level -- Bluff (Cha), Concentration (Con), Craft (Int), Hide (Dex), Intimidate (Cha), Knowledge (arcana, history, local, the planes, religion) (Int), Listen (Wis), Move Silently (Dex), Profession (Wis), Sense Motive (Wis), Spellcraft (Int) and Spot (Wis).
Spell-Like Ability can be used once every 1d4 rounds.
Save DC is 10 + 1/2 class level + Cha bonus.
At every level, choose any available spell-like ability. You gain two daily uses of that spell-like ability. You can take a lower-level spell-like ability if you want -- the following table lists the earliest level at which each ability becomes available.
Level: Available Spell-Like Abilities
1: Cause Fear, Bane, Doom, Ray of Enfeeblement
3: Scare, Summon Swarm, Hold Person, Silence
5: Animate Dead, Fear, Bestow Curse, Slow
7: Confusion, Crushing Despair, Poison, Lesser Planar Ally
9: Slay Living, Insect Plague, Magic Jar, Nightmare
... etc.
Easy for a DM to run, lower power than a PC for sure.
-- N