The business deal was left a bit inconclusive in my opinion. Even though Maou got the businessmen to agree to it by reminding them of profits, they still left without knowing what she was going to gain from the deal. She did act like an inexperienced girl to a degree (somebody who could be ripped off), but considering she was offering the traders something novel that could generate huge profits, I doubt they could have bought that act entirely, especially with the compass and everything. I can't help but wonder if that was indeed exactly how Maou had planned: To leave the men partially in shadow and doubt, wondering what manner of a scheme she would later use to realise her own gains, or if it was just a flaw in the script.