Al's Coins - Buy and sell error coins.
Byers Numismatic - Buy and sell the worlds finest mint errors.
The Error Collection - Buy and sell error coins of all kinds.
Error Trends Coin Magazine - A monthly publication dedicated to serving the error coin hobby.
Fred Weinberg & Co. - Fine mint error coins, U.S. type, and world coins.
Ken Potter - Price Lists on Error Coins, U.S. Defaced Coinage Dies.
Rich Schemmer Error Coins - Specialties: Numismatic Errors, U.S. Patterns/Trials.