Hi Sharinole,
A mattress is only as good as the quality of the layers that are inside it but depending on the specific mattress, the retailer, and the prices charged … Natures Sleep can be good quality/value choices IMO.
They are made in China but they are CertiPur certified for safety (like most North American foam) and they also tend to use good quality materials (typically 2.2 lb base foams and memory foam from about 4.6 lb density and higher). They have been open and responsive when I talked with them on the phone.
A few of the comments about them (or some of the specs for some of their mattresses) are in post #2 here and in post #6 here and in post #2 here.
I don’t know the specifics of which one you are looking at but a big part of the value of any mattress purchase is making sure that it is suitable for your needs and preferences in terms of PPP (Pressure relief, Posture and alignment, and Personal preferences) which means that the ability to test it personally or at least work with someone online that has the knowledge and experience to help you make choices that are suitable for your body type and sleeping positions is just as important a part of “value” as the quality of the materials and the price you pay. At least they are generally in the better quality range though.
Phoenix