Infracost Atlantis Demo
See this pull-request for a demo, expand the Show Output sections and scroll down to see the Infracost output.
The Infracost Atlantis integration runs Infracost against $PLANFILE that Atlantis generates. It automatically adds a comment to the bottom of Atlantis' output showing the cost estimate difference if a percentage threshold is crossed.
See the Infracost integrations page for other integrations.