The Grotesequerie is one of the most popular formations from the covens supplement. There is a recent thread https://www.thedarkcity.net/t14740-grotesquerie-how-do-you-run-it
discussing how to run it.
Dark Artisan and Corpsethief Claw are also well regarded. Just be wary against marine armies with lots of grav weaponry with the CTC. Check out some of the Tabletop Tactics youtube videos to see the CTC in action.
Two boxes of Crypt Horrors, two Talos kits and a Haemonculus would allow you to build a Talos, a Cronos and convert two units of three Grotesques with the Crypt Horrors and leftover bits from the Talos sprues, allowing you to run the Grotesquerie or the Dark Artisan relatively cheaply money wise.
The scalpel squadron can also be used if you want to use null deploy tactics.
I danced with Fate, she said it could go either way.