You can follow the link for SKR's ideas on pricing. Strangely enough, the ideas themselves are mostly good, it's just how he applies them that's borked. Apply a bit of common sense and they should serve you well. Mostly, though, I just eyeballed:
- 10 FP: this feat is excellent, a high priority for any relevant characters
- 8 FP: this feat opens up some new tactical possibilities or expands existing ones significantly
- 6 FP: this feat is decent, but the sort of thing you'd otherwise pass over for lack of feat slots
- 4 FP: this feat is weak, and generally not worth thinking about except for highly specialized builds