I know Petra is expensive, but worth it. If it where me, I'd play survivor and save for her. Also Vladimir is cheap for a reason, Toro or Methane are beter, and more expensive options.
Gheist is just an expensive clan to play in general.
Try Ula Wula. Cards like:
Jeff (last resort)
kirk (in a few weeks)
then you can pair them with All Stars:
Alison (last resort)
Two VERY cheap starter clans with teeth.
If those don't work you have roots:
Cheap and quality cards - usable in the future - and easy to upgrade.