Buy or Sell with Expert Advice from Maine's Leading Business Brokerage and Commercial Real Estate Firm Located in the city of Portland, Magnusson Balfour, a division of Keller Williams Realty, is a leading resource in Maine for commercial real estate and business brokerage services. We can help you with selling, leasing or buying commercial property and selling or buying a business. We also provide guidance in any of these areas on a consulting basis. With over 50 years of experience, we have comprehensive knowledge and the specialized expertise our clients need to succeed.