Hi WebbyR,
In general … if your springs are squeaking or if your mattress has developed soft spots or “hills and valleys” then a topper would be a temperory or partial solution at best and it’s time to replace the mattress. At 14 years old you are well beyond the useful life of most mattresses. There is more about “fixing” a mattress that has developed soft spots (or was too soft initially) in post #4 here.
When you are looking for a new mattress … the best place to start is post #1 here which will give you the basic information, steps, and guidelines you will need to make the most suitable and informed choice (and avoid the worst ones including the major brands and most mainstream mattress stores and chain stores). Things have changed a lot since 14 years ago. “Brand” shopping is one of the worst ways to choose a mattress.
Once you get to step 3 in the guidelines, then the next step is to research which manufacturers or retailers to visit before you begin to test mattresses (there is little point in testing mattresses where you won’t be able to find out any meaningful information about the materials that are in the mattresses you are testing.
I’m not sure where on the Mississippi Gulf Coast you are but there are links to the forum lists along the Gulf Coast in post #3 here and the Gulfport list would probably be the closest to you.
Better retailers and manufacturers don’t need “sale prices” to have good value every day of the year (see post #5 here about “fake sales”)
Phoenix