Hi tknx,
Some of the better posts about children and mattresses with goo information and links to some good sources are listed in post #2 here.
The better choices I’m aware of in the NYC area are listed in post #2 here and there is a more categorized list with some more detailed descriptions in post #7 here.
I think that Mark at Dixie foam would be one of the first local places I would visit if I was in your shoes.
Phoenix