From what I understand, the Promoted Post fee varies by your number of friends. My friend with ~400 people said Facebook wanted to charge her $7 for post advert

From what I understand, the Promoted Post fee varies by your number of friends. My friend with ~400 people said Facebook wanted to charge her $7 for post advertisement... someone who commented said that her own rate would be $90, apparently because she had 5,000 friends on there.