Its 36k comms for rank 7 and above Creeps, 35k comms for Freep armour. Unless you're a Spider or Warg, then you have to buy skills too, (6k comms) and no, they aren't available in the store. You're slipping turbine, I would have bought my rank 4, 5, and 7 skills on my rank 11 spider from the store.