Hi burritolicious,
The first place I would start your research is the mattress shopping tutorial here which has all the basic information, steps, and guidelines that you will need to make the best possible choices in any budget range … and know how and why to avoid the worst ones.
Once you get to step 3 … if you let me know your city or zip code I’d be happy to let you know about any of the better options or possibilities I’m aware of in your area.
If you are also open to purchasing online then the tutorial also includes several links to lists of some of the better online sources I’m aware of but to help you narrow them down, posts #3 and #4 here includes some of the better online sources for lower budget latex or latex hybrid mattresses I’m aware of and post #4 here includes some of the better online sources for lower budget memory foam, polyfoam, or innerspring mattresses I’m aware of as well
I would always make sure that you know the quality of all the materials in any mattress or topper you purchase so you can identify any lower quality and less durable materials that would be weak links in the mattress and make more meaningful comparisons to other mattresses.
I would also tend to avoid buying a mattress/topper combination unless you can test the combination in person (see post #2 here).
Phoenix