Hi cstafford2009,
The materials are manufactured in the US.
I’m not sure what I can add to the information you’ve already read about the quality/durability of the materials in the Helix mattress. They meet the minimum guidelines that are in the quality/durability guidelines here and for most people that aren’t in higher weight ranges there are no obvious weak links in the mattress that would compromise the durability and useful life of the mattress although as you mentioned some of the layers and components also aren’t the highest quality/density materials available either. Of course you also won’t find the highest quality materials in every layer and component in mattresses in these budget ranges and there are always tradeoffs involved when you are looking at a mattress that sells for under $1000.
The Dreamfoam Ultimate Dreams uses 3" of blended Talalay latex (in your choice of firmness level) and a 1.8 lb base foam (which is a little higher quality/density than the Helix sleep) and a cover that is quilted with 1.5" of polyfoam so there are no weak links in this mattress either.
The 2" of 3 lb memory foam in the Leesa is a lower quality/density material than the minimums in the guidelines and I would consider it to be a potential weak link in the mattress (although the 2" of Avena polyfoam above the memory foam would improve the durability of the memory foam somewhat compared to having the same material in the top layer of the mattress)
There is also more detailed information about the many variables that can affect the durability and useful life of a mattress relative to different people in post #4 here
Phoenix