Have you looked at the American Personal Chef Association? and then there is the Personal Chef Network, I think.
American Personal & Private Chef Institute & Association - Professional Personal Chef Training Personal Chefs Network - Become a Personal Chef
Being in Oz, I am probably not much help but I tried!
ETA: I run a national network of pc's in Australia. So, as much as I dont personally know the American market firsthand, I CAN say, I do know pc's in Australia and am planning to do some 'research' business trips in the near future to CA and USA. I also have Candy Wallace's book and found it an interesting read.