Cheese expert Steve Jenkins, author of Cheese Primer, says it's just too difficult to find real Brie in the United States. His advice is to forget it entirely. Instead, consider the excellent alternatives that are available (some from surprising sources like Wisconsin.) Here's some suggestions:

Reblochon from France, and any of the Toma cheeses from Italy.
Camembert: Look for Le Chatelain, or those from Isigny or Chaource.