Costs function much like negative Dividends. They are the harmful effects of the effort to reach the Goal. Look at the Requirements for your story and see what Type of Costs might make that effort more taxing. Look at the Consequences for your story and see what Type of Costs might seem like an indicator of what might happen if the Goal is not achieved. Look at the Forewarnings and determine the Type of Costs that increases the Forewarnings, or possibly obscures the Forewarnings from your characters. Finally, look at the Dividends and try to find a Type for Costs that balances the positive perks. To balance Dividends, Costs need not be an exact opposite, but simply have the opposite (negative) effect on the characters.