There are no costs in the rules. Why? Everyone asks that question and the answer is not really given.
The e-Ferret is an emerged ferret, so really really rare <1% of the ferret population. Technocritters are a new phenomenon, maybe the authors thought we don't need prices for such new and rare stuff.
The same is true for AI, they are to rare and you can't mass produces them, they have to evolve by themselves.
As GM the best way for now is to let the player in the dark that such animals do exist. And if he want to give one player such rare being, than he should give his PC a stray one, from the street or wild.
Maybe the RW Authors have a supplement for us in their box, but for now, there are no official prices or costs per month.
Btw: What costs a AI that does not have a home node (like the PC-AI) per month? It is a good question... they only need their food supply and the Matrix, or do I forgetting something?
Yours faithfully,
UV