Hi omadam,
If by “organic” you mean a mattress that is certified organic or that is made only from materials that are certified organic even if the mattress itself isn’t certified organic (which would include organic latex and organic wool and other natural fibers) then your budget would be too low to reasonably expect to find a mattress that fit your criteria and used only materials that were certified organic. There is more about organic certifications in post #2 here and the post it links to.
If on the other hand you are open to considering either “natural” or “mostly natural” materials or even “safe” materials (even though they may not be organic or natural) then you would have many more options in your budget range even though they wouldn’t be certified organic.
There is also more information in post #2 here and the more detailed posts and information it links to about safe, natural, organic, “chemical free”, and “green” mattresses and mattress materials that can help you sort through some of the marketing information and terminology that you will encounter in the industry and can help you differentiate between them and answer “how safe is safe enough for me” or “how organic is organic enough for me” so you can decide on the types of materials you are most comfortable having in your mattress. These types of issues are complex and are generally specific to each person and their individual sensitivities, circumstances, criteria, beliefs, and lifestyle choices.
Once you have decided on the type of materials you are comfortable with having in your mattress then you will be in a much better position to begin researching mattresses that are the best “match” for your criteria and that are inside your budget range. The first place I would start your research is the mattress shopping tutorial here which includes all the basic information, steps, and guidelines that you will need to make the best possible choices.
The tutorial also includes a link to a list of the members here that sell mattresses online (in the optional online step) that all compete well with the best in the industry in terms of their quality, value, service, and transparency and many of them also make latex and latex hybrid mattresses that use different types and blends of latex (including some that use organic latex and wool fire barriers) that have a range of different designs, options, features, return and exchange policies, and prices that would be well worth considering.
Some of the lower budget latex and latex hybrid mattresses I’m aware of are also listed in posts #3 and #4 here.
If you let me know your city or zip code I’d also be happy to let you know about any of the better options or possibilities I’m aware of in your area as well.
Phoenix