Ask what kind of extra services dealers provide.

Numismatic Guaranty Corporation of America. (NGC)
P.O. Box 1776 Parsippany, NJ 07054 (201) 984-6222
Professional Coin Grading Services (PCGS)
P.O. Box 9548 Newport Beach, CA 92658 (800) 447-8848
American Numismatic Association (ANA)
818 N. Cascade Avenue Colorado Springs, CO 80903 (719) 632-2646
Industry Council for Tangible Assets (ICTA)
6728 Old McLean Village Drive McLean, VA 22101 (703) 847-1740
Professional Numismatists Guild (PNG)
P.O. Box 430 Van Nuys, CA (818) 781-1764
U.S. Postal Inspection Services - Postal Fraud Division
475 L'Enfant Plaza, S.W., Room 3517 Washington D.C. 20260 (202) 268-4505
Federal Trade Commission (FTC)
Check your local listings
State Attorney General
Check listings in dealer's state capital.