Hi chicago77,
This is mainly because the manufacturers of the mattresses (possibly from from China) don’t provide the information to their retailers that lets their customers make an informed choice. In addition to that most consumers don’t realize the importance of knowing the foam densities in a mattress and the sad reality is that if you have spent more than a couple of hours on this website then the odds are high that you know more meaningful information about mattress materials than the majority of the salespeople in the mainstream industry that sell them.
It would be somewhat unusual in most of the mainstream industry to find a mattress that would have a reasonable expectation of lasting for 10 years in your budget range although there are certainly options available to you that would meet the foam quality/density guidelines here that would.
The link I posted in my previous reply included some of the better options that are local to you and post #4 here and the posts it links to also includes some of the better lower budget online options I’m aware of as well that may also be worth considering and would likely meet your criteria as well.
Broyhill mattresses are private label brands made by Boyd Specialty Sleep (see here) and they use the same materials including their “engineered latex” which is really just “latex like” polyfoam with surface modifications that will “feel” something like latex in a showroom but don’t have nearly the same durability. This is the type of information that many years of research into mattresses and mattress materials and thousands of hours of conversations with retailers and manufacturers uncovers. While the some of the Boyd mattresses do include some “real” latex … if you were to purchase this mattress for example which includes “engineered latex” in the description and doesn’t have any “real latex” you would find that the law tag describes the materials as polyurethane foam.
This would be a good minimum criteria for memory foam (as long as you aren’t in a higher weight range above the lower 200’s or so where I would reduce or minimize the use of 4 lb memory foam) but for polyfoam a minimum density that I would generally consider in a one sided mattress would be in the range of 1.8 lb density (memory foam and polyfoam come in different density ranges).
If you can find out the information listed here about all the layers and components in any mattress you are considering and post them on the forum then I’d certainly be happy to make some comments about the quality or durability of the materials or the mattress as a whole. I would also make sure you know whether the foam materials in the mattress were manufactured in North America or in China. Post #6 here has more information about the additional uncertainty and risk that can be involved in purchasing a mattress that has materials that are made in China.
Phoenix