This totally varies, as you increase targeting, with Look-a-likes, custom audiences, retargeting, etc your CPI should theoretically come down as your most relevant users convert better.

Typical CPIs range but typically can sit as low $5CPI or as high as $25CPI again depending on the cohorts you are trying to reach. Typically gaming is pretty competitive with companies, individuals, bidding very aggressively on an oCPM against potential paying player mobile gaming cohorts.

Facebook moved away from the precise interest targeting they had as they have been looking for people to upload custom audiences and create look-a-like audiences of your existing customers. These, theoretically, depending on your vertical, again should convert much better than interest targeting.