Hi adonohoo.
Serta doesn’t fully disclose the type and quality of the materials in their mattresses and also tend to use lower quality and less durable materials in their comfort layers as well and unless you are able to find out all the information you need to make an informed choice about a mattress (see this article) I would avoid them completely no matter what your budget range (see the guidelines here ).
I think that testing mattresses made by major manufacturers can end up doing more to confuse than to help because no matter how they feel in a showroom … you are making a blind purchase and since you can’t feel quality or durability all that happens is that you waste a lot of time testing mattresses that aren’t worth buying but also can’t be used as a reference point or compared to other mattresses. This is the reason for the first guideline in this article which suggests avoiding them completely (and the chain stores that sell them) The only exception I would consider is if I knew the quality of all the materials and layers and they were good quality materials and value which unfortunately you aren’t likely to find. Excluding the worst choices (which is probably about 75% of them or more) will help you focus on the better ones without being overwhelmed and frustrated by the lack of information or misleading information that you will encounter or worse yet spending the time and adding to the confusion.
There are also some guidelines in post #1 here which can greatly increase your chances of finding the most suitable mattress that has the best possible quality and value.
While you usually won’t find a mattress that is “equivalent” to a mattress you have tested locally made by a different manufacturer that is available online … in some cases the “art and science” of approximating a mattress has already been done to a large extent and an online manufacturer or retailer may have already “matched” their mattresses to a specific mattress that is available locally and included which mattress it “approximates” in their description.
One of the mainstream mattresses that I would use though for testing purposes though is Tempurpedic because they can be a model for other memory foam mattresses with similar or better quality and much better value. Most manufacturers of memory foam mattresses have a good idea of how their mattresses compare to the various Tempurpedic models and some have even designed and tested their mattresses to be as similar as possible in terms of both feel and performance and the type of layering and materials inside.
Many of our Trusted Members here are offering very good quality choices that are within your budget range, but the first suggestion I would have is to start with the tutorial post here which has all the basic information, steps, and guidelines you will need to make the best possible choices … and know how and why to avoid the worst ones which would include the major brands such as Serta or any mattress where you aren’t able to find out the quality of the materials inside it.
Hopefully this will help you bypass most of the misleading information, confusion, and frustration of mattress shopping, connect with people who put your long-term interests above their own, and of course … you are always free to post on the forum if you have any questions along the way.
Phoenix