Hi Skubaman,
Post #2 here and the posts it links to has more information about organic, natural, chemical free, green, and safe materials that should help you decide on which materials you are comfortable having in your mattress and to help answer the question “how safe is safe enough for me?”
If you are comfortable with an Oeko-Tex certification then any type of natural, synthetic, or blended latex would be suitable for you (all the latex you are likely to encounter would be either Oeko-Tex or Eco-Institut certified).
If you are comfortable with a CertiPUR certification then almost any foam material would be suitable for you since there are many polyfoam and memory foam options that are CertiPUR certified.
Your budget is certainly enough to include some very good quality all latex or latex hybrid mattresses. The better local options or possibilities I’m aware of in the San Francisco area (subject to the guidelines here) are listed in post #2 here and the mattress shopping tutorial includes this link to a list of the members here that sell mattresses online and many of them make latex or latex hybrid mattresses that use different types and blends of latex with a wide range of designs, options, features, and price ranges that would give you many choices.
Phoenix