When he restored the money to his mother, his mother took two hundred [pieces] of silver, and gave them to the founder, who made of it an engraved image and a molten image: and it was in the house of Micah.
This is one of the most important statements in  Judges 17.  The author of this narrative evidently believed that a king in Israel would have prevented the formation of such an illegal shrine.  Hervey thought that this indicates that the author might have lived in the days of Asa or Jehoshaphat.[21]  However that cannot be correct.  No author who lived after the first few honeymoon years of Saul's reign could have supposed such a thing.  The record of Israel's kings from Solomon and afterward was one of shameful compromise with idolatry and the open acceptance of it.  This verse practically nails down the time when our author (of Judges) lived as being in those first few years of the reign of Saul.  This points to SAMUEL.  The truth of the business is that "If Israel had had a king," he would have led the way in idolatry, as proved by the vast majority of them. Only the innocent SAMUEL could have supposed such a thing as that which is implied here.  Anyone except him would have implied, that, the right kind of a king was needed to prevent every man from doing what was right in his own eyes.