Not a while lot to work with here.
If you bought a Vassal of Menoth, you could have the following 50 point list
pKreoss
-Reckoner
-Redeemer
-Crusader
Bastion Seneshal
-Repenter
-Vanquisher
max Bastions
max Errants
min Choir
Vassal of Menoth
and the following 35 point list
eKreoss
-Crusader
Bastion Seneshal
-Vanquisher
max Bastions
max Cinerators
max Errants
Its not an ideal
eKreoss list. Normally you want to run as many weapon masters as possible.
An ideal
eKreoss list would look like this
eKreoss
-Crusader
Bastion Seneshal
-Repenter
max Bastions
Knights Exemplar
Knights Exemplar
max Errants with
UA
KE Seneshal(free)
As for what you want to buy,
Epic Kreoss loves weapon masters. Especially Knights Exemplar. A couple units would suffice.
2 Vassals of Menoth. Great toolbox solos.
the Errant
UA. I cannot stress how awesome this makes them.
Rupert Carvolo. He can pass out tough or pathfinder to our units, which is awesome.
Covenant of Menoth. Combine his no Knockdown ability with Rupert's tough and things get awesome. Plus he can shut down the enemy caster if close enough.
Gormen. Like Rupert, he's an amazing solo. His Acid Bombs can obliterate a clumped unit of infantry while Black Oil(Blind) is debilitating to every single model in the game, except for Harbinger. Rust bomb is as good as +2
str against a warjack.
Exemplar Seneshal. You will need at least 1 for
eKreoss's tier list because you get one for free. He's better than the Errant Seneshal, the other free option, much more durable and hits harder.
The Bastion Seneshal's marshal ability is best for the Repenter and the Vanquisher because they usually only ever need a single focus and the Jack Marshal ability is basically a point of focus. Plus he can heal your bastions.
Run him and the Vanquisher behind the Bastions(maybe with Defenders ward on them

) They can protect the Seneshal and the Jack from getting charged while the Vanquisher lobs fire at the enemy(remember the Bastions may block
LoS so leave gaps)
I would recommend converting the Cinerators into more Bastions. You could buy the appropriate bastion parts from
PP direct or simply replace their sword hands with a third party polearm of some kind(I used
GK Halberds and they fit perfectly) This would give you a more useful second unit of Bastions who can also benefit from the Seneshal.
pKreoss plus the Redeemer is the classic Pop'n'drop tactic.
Load the Redeemer up with Focus, Activate Kreoss and pop Feat to knock down enemy warcaster, Battle the Redeemer with the choir, shoot knocked down warcaster with Redeemer, win game.
With the Choir bonus you'll be hitting a knocked down caster on anything but snake eyes even with Inaccurate. And almost no caster can take 4 pow14 hits(one being boosted damage) to the face and live. The 4th hit comes from the Ancillary attack ability of the Vassal of Menoth. Any of our ranged jacks can also get in on the action. A Reckoner can plant a boosted pow15 hit on the enemy caster. A vanquisher can put a pow16 and light them on fire.