a coin dealer is not automatically an MSB -- coin collecting/trade/investing is not the same thing necessarily as currency exchange. They might be high risk however, if they buy/sell with large cash transactions. Coin dealers vary from small collectors to sophisticated investment sellers/buyers. Look at some of their transactions and chat with them about who their customers are- US only or international, known collectors or periodic large dollar traders. I think this is similar to retail stores and others on the high risk list-- they could be laundering money, but most are not.