@Spitfire
I believe you are not profiting from the suits even though you win the contest. A contest have multiple participants and there are chances that you may/may not win. You made a costume in the likeness of someone's else IP. You in no way said you represent Microsoft in the contest. Hence, you did not violate any copyright law.
You are however liable to report your winning as income and IRS has the authority to lock you up in case you failed to report the earnings.
I believe you are not profiting from the suits even though you win the contest. A contest have multiple participants and there are chances that you may/may not win. You made a costume in the likeness of someone's else IP. You in no way said you represent Microsoft in the contest. Hence, you did not violate any copyright law.
You are however liable to report your winning as income and IRS has the authority to lock you up in case you failed to report the earnings.