Hi dave36251,
As you are discovering … where you buy a mattress can be a more important first step than researching which mattress to buy. In general … factory direct manufacturers or smaller sleep shops that carry independent or local brands will not only be more informative about what is in their mattresses … they will sell mattresses that use higher quality materials at lower prices than major brands or mass market outlets and chain stores (who are benerally trained in marketing techniques much more than they are in the differences between mattress materials and components).
The first suggestion I would have is to read these guidelines. This will help you avoid the majority of the worst choices you could otherwise make.
The next step I would suggest is to scan (not study) the overviews in the mattresses section of the site. This will give you enough basic knowledge to ask better questions and to know when you are being “sold” a story or when someone is more focused on educating you about their mattresses.
Finally … there is a list of some of the better factory direct manufacturers and outlets in the NYC area in post #2 here and a more categorized list and descriptions of many of them in post #7 here. These are the ones (especially the last 5 in the second list) I would focus on.
Hope this helps (especially to keep you out of chain stores and away from major brands) and feel free to post any questions you may have along the way.
Phoenix