Hi Sweet Dreams,
I realize you are trying to be helpful and I certainly appreciate the intent but there is little point in trying a mattress unless you are also able to find out the type and quality of all the materials inside it because the only thing you will be able to tell is PPP (Posture and alignment, Pressure relief, and Personal preferences). If you can’t find out the type and quality of the materials inside it then you won’t know anything about the durability or useful life of a mattress (see post #13 here about the most important parts of the value of a mattress purchase).
There would be little “value” in buying a mattress that is “perfect” in terms of PPP if the materials in the mattress are likely to soften or break down too quickly relative to the price you paid.
Phoenix