Hi Renaissancelady46,
Subject to first confirming that any retailer or manufacturer on the list that you wish to visit is completely transparent (see this article) and to making sure that any mattress you are considering meets your criteria and the quality/value guidelines here … the better options or possibilities I’m aware of in and around the Asheville/Hendersonville, NC area are listed in post #4 here.
The thickness of a mattress is just a side effect of what the layers and components that are used to make it and achieve the design goals and the feel and performance of the mattress add up to. Depending on the type of mattress and the materials and components inside it … different mattresses can range from about 6" thick (usually firmer mattresses with less padding) to much taller than your 13" mattress. If they used less layers or components (or different layers and components) then the mattress would feel and perform differently.
If you are shorter than average then it would certainly make sense to use a lower profile bedframe and foundation or a lower profile platform bed so that your sleeping surface is at a height that you are more comfortable with when you get in and out of bed or sit on the side of your mattress.
Phoenix