At $6, Anafenza the Foremost looks like a pretty good buy. However, the real opportunity is with foil versions. While having a prerelease foil version has kept down the set foil prices a bit, foils of this mythic rare Legendary Creature should NOT be only $10. Anafenza is a decent Green/Black/White "+1/+1 counters matter" Commander. While Ghave, Guru of Spores is considered the premier Commander of that archetype - as he can also create tokens - Anafenza has her own decent brand of aggression.
If you're looking to pick up Anafenza, the Foremost, foils look like the way to go. If she becomes a staple in the new Standard format, foils could double (or more) overnight. If not, it's hard to see her foil ever being worth less than $10 anyway. Seems like a decent pick-up.