Sounds like the estimate here just covers the cost of a public outreach campaign to notify voters (some of which may need to be redirected to tell voters what the law is as it stands now).

But particularly since Wisconsin’s law affected absentee ballots as well, I wouldn’t be surprised if implementation of the new ID law would also have involved extra costs in processing absentee ballots and trying to reach voters who did not submit copies of their ID with their ballots.  Or the costs of processing additional provisional ballots at the polls.