It feels like too many. I just counted and I've gotten 14 so far. Then again, it's fun to watch my skill time for TR2 go down every time I get one. They still all make a noticeable difference.
That's my question... How do you compute for the cost of the card? I got a total of +4 (a +3 and a +1) for 10k per point (total=40,000i) but now these two brain cap cards (a +5 and a +3) for 20k per point (160,000i total).