Hi feeblewitz,
I think you are wise to avoid Stearns & Foster or any of the major brands not just because of fire retardant issues (which may or may not be an issue of safety depending on the specific type they use) but because you won’t be able to find out the quality of the materials inside it (there is much more about this and other mattresses to avoid in the tutorial post). The major brands tend to use lower quality materials in the comfort layers than I would be comfortable with and they don’t disclose the information you would need to make an informed choice so they would be a very risky purchase. There are many instances on the forum of members who have purchased them and within a relatively short time need to replace their mattress because of foam softening and breakdown of the comfort layers and there is no warranty coverage because the visible impressions aren’t deep enough and the loss of comfort and support isn’t covered by warranties.
Probably for a local purchase but not for an online purchase. The tutorial post includes a link to some of the members here that sell latex mattresses online with a wide range of features, options, designs, price ranges, and return or exchange options and some of these would be in your budget.
I would personally never consider a mattress where the information you need to make an informed choice about the quality of the mattress and the materials inside it isn’t available to you. It is one of the most common causes of buyers remorse or in many cases mattress surgery within a very few years.
Phoenix