I live in Brooklyn, NY. Suddenly and without warning, my local coin dealer closed his shop with no advance warning. How can I find a new dealer? The dealer was A Omega Coins.
Of course you can visit some local coin shows & network with all the dealers & attendees. You could also look in your local yellow pages for local shop listings. If you have the original guys email address (or Website), you might still be able to contact him that way.
Try Brooklyn Gallery of coins and Stamps.... They have a website for coin supplies and books, but do sell USA & World coins. They issue a coin catalog twice a year. There are literally thousands of coin dealers with web sites as pennywise suggested. There are quite a few in New York City (most can be found in the Yellow Page Directory), Clinker