Hi tntcater,
Just in case you haven’t read it yet … the tutorial post here is the first place I would start your research and has the basic information, steps, and guidelines you will need to make the best possible choices … and know how to avoid the worst ones.
I would be cautious at Ashley Furniture and make sure you know the actual materials in any mattress you are testing there. What many people call a “latex mattress” may only have a relatively thin layer of latex inside it and the top layers which are most important may not be latex at all.
The better options and possibilities I’m aware of in and around Evansville, IN are listed in post #18 here. The St Louis / Carbondale list is in post #6 here and the list that includes the Champaign/Springfield/Peoria area is in post #2 here and the Indianapolis list is in post #2 here.
Your budget is certainly enough for a good quality mattress but may be on the low side for “all latex” (depending on the type of latex) although it would still be in the range of a latex hybrid. I don’t keep a list of mattresses for each area based on price or specific construction (this would be more than anyone could keep up with in a changing market) so price and specific mattresses would be the part of your research that would be up to your phone calls and visits but you would certainly have some good options available.
I would tend to avoid trying to figure out the choice that would be best for you ahead of time based on specs and would focus on your own careful and objective testing using the guidelines in the tutorial post (see mattress firmness/comfort levels in post #2 here). Your husband is in a higher weight range so in very general terms he may find that a thicker mattress works better for him (see post #14 here about mattress thickness) but your own testing on a specific mattress is the best way to know with any certainty.
Phoenix