Hi lakosil,
The first place I would start your research is post #1 here which has all the basic information, steps, and guidelines that can help you make the best choices.
A mattress is only as good as it’s construction and the quality of the materials inside it. A mattress will generally soften and break down from the top down so the quality and durability of the comfort layers is one of the most important factors in the useful life of a mattress. While there are may people who have wrestled with the idea of purchasing many lower quality mattresses more often vs a higher quality mattress less often … in most cases you are much better off with higher quality because lower quality mattresses may not even last as long as you think they will and when the materials soften or break down more quickly the more rapid loss of comfort and support leads to lower quality of sleep even if you can still “tolerate” it.
They have just re-introduced the Serenity memory foam mattress which uses 5 and 8 lb memory foam and high quality polyfoam in the comfort layers. If your testing indicates one or the other is a good match in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) it would be well worth considering in terms of quality and value.
Some of the other options and possibilities in the Orlando area I’m aware of are listed in post #2 here including Fox Mattress who is of the members here who I think very highly of and competes well with the best in the industry in terms of quality, value, and service.
You can see some of my thoughts about buying a mattress from a big box store in post #4 here.
Phoenix