An ethical and professional locksmith that wants your repeat business will give you an accurate quote on the phone. Reputable locksmiths need your repeat business and want to provide good prices and great customer service. Call around and find a local locksmith company that is registered with your local Chamber of Commerce or that is a member of a Professional Locksmith organization. Ask their prices, hours, and most of all ask about their business and professional licensing. The best locksmith is one who cares about your concerns and wants to help.
Avoid being scammed by finding a reputable locksmith that has good references and who is licensed and insured.