Hi Send2nancy,
The most important part of the “value” of a mattress is how well it matches your own specific needs and preferences in terms of PPP (see post #13 here).
Outside of your own personal testing for PPP, a mattress is only as good as its construction and the quality of the materials inside it regardless of the name of the manufacturer on the label. In the case of the mattress you are looking at, all the materials are high quality and there are no obvious weak links in the mattress. It would be comparable in terms of durability to any other mattress that used similar materials.
There is more about the many factors that can affect the durability and the useful life of a mattress in post #4 here and there is more about the different types and blends of latex in post #6 here and in post #2 here but blended Talalay latex is among the most durable types of foam available.
You can also read a little more about the polyfoam “stabilization layer” on the bottom in post #2 here. I believe they use 1.5 lb polyfoam but this wouldn’t be a durability issue on the bottom of the mattress.
I would also find out more about the type of cover and whether it includes any polyfoam in the quilting (and if it does then I would confirm that it isn’t more than “about an inch or so”).
Depending on the area, the prices, the retailer, and the parts of your personal value equation that are most important to you … the Restonic Healthrest mattresses can certainly be “better than average” value compared to other mainstream mattresses that use similar quality materials.
Phoenix