The federal trademark registration fee is $375 for paper filing and $325 for electronic filing per international class. Use in commerce defines your right to file. You should and could learn more from the website at www.uspto.gov. I leave to Wisconsin counsel the question of state registration of trademarks.
The above is general legal and business analysis. It is not "legal advise" but analysis, and different lawyers may analyse this matter differently, especially if there are additional facts not reflected in the question. I am not your attorney until retained by a written retainer agreement signed by both of us. I am only licensed in California. See also avvo.com terms and conditions item 9, incorporated as if it was reprinted here.