Hi msalerno,
The “value” of a mattress purchase is always relative to how it compares to other similar mattresses. There is more about the most important parts of the “value” of a mattress purchase in post #13 here that can help you make more meaningful comparisons between your “finalists”.
There is also more in post #6 here about “negotiating” and making more meaningful pricing comparisons but the most effective approach would be to compare the mattress you are considering to other mattresses that have a similar design and materials regardless of the specific model or brand.
Phoenix