Hello KDSPUCK,
The Relax the back Pure Fit are made by a company called Anatomic Global which is a subsidiary of Foamex/FXI which makes Aerus, Sensus, and other foams made by a process called VPF which I believe produces some very high quality foam. Anatomic Global produces the EcoSeries of mattresses. The description on Relax the Back implies quite clearly that they are using Aerus memory foam (more breathable than many other memory foams) but doesn’t say the density of the foam they use or the layer thicknesses however and IMO the mattresses there appear to be overpriced compared to other mattresses that use the same foams.
ADMIN NOTE:Removed 404 page link | Archived Footprint 1: anatomicglobal.com/| Archived Footprint 2: ecomemoryfoam.com/
Polyfoam and memory foam (which is basically polyfoam with additional chemicals added to make it less elastic and more viscous) are both made from 2 primary ingredients. These are an Isocyanate and a polyol. The isocyanate is most commonly TDI and less commonly MDI. Both the polyols and the isocyanate are petroleum derived. In the new so called “green” generation of both polyfoam and memory foam … some of the polyols have been replaced with plant based polyols from soy, linseed, palm, sunflower, castor oils and others. The percentage that is replaced is usually quite small (under 20%) however there are a few foam manufacturers … primarily in Europe … who are replacing up to 50% of the petro based polyols with plant based polyols. Assuming an approximate 1:1 ratio of polyols to isocyanates (just to make the math easier), this would mean that with 50% polyol replacement … about 25% of the foam would be “plant based”. With about 20% polyol replacement … then about 10% of the foam would be plant based. It’s a small step in the right direction but only a small step. In other words … most of the “eco” claims for polyfoam are mostly “greenwashing”. They are still polyfoam or memory foam which are made from chemicals with just a little bit of highly processed plant oils in them. At the current state of techology … 50% polyol replacement is about as high as is possible while keeping the desirable qualities of the foam. Anatomic Global is replacing about 30% of the polyols (about 15% of the foam would be plant oils) which is higher than the norm. This article is also well worth reading.
There are a wide range of different firmness levels and layering combinations available in latex which can result in almost any feel and combination of comfort and support that is needed from very very soft to very very firm and everything in between. The different types of latex (Dunlop and Talalay) can also make a significant difference as well as the finish, quilting, and ticking of the mattress.
As a whole … the best value in a mattress will be at a local factory direct manufacturer but not all local manufacturers have the same value or quality. They will range from small “mom and pop” outlets to multi-million dollar businesses and everything in between. Many of them produce exceptionally high quality and value mattresses (a higher percentage than any other mattress source) but I have also encountered some who are more like most major manufacturers where profit and sales and “stories” overwhelm service and value. While these are always disappointing to me, they are less common in the factory direct manufacturing “group”. I call them “money machines” vs “mattress people”.
I’d certainly be interested in your experiences and where you went if you are comfortable sharing this as this type of feedback is always valuable. I’d also be happy to let you know of any local manufacturers I am aware of near you (unless they are already listed in another thread and you know already) and any knowledge I may have of them based on either feedback or conversations I have had with them.
A few online outlets that may be a good reference point to compare with Relax the Back memory foam options are in post #12 here.
Feel free with any further questions or comments along the way 
Phoenix