Hi dwzemens,
The Leesa has 4" of material above the support core which would be more costly than using 3" of the same materials (and more lower quality/density materials would increase the risk of premature foam softening and breakdown even though it would add to the cost of the mattress) but there are many other variables that factor in to how each manufacturer prices their mattresses but this type of information is proprietary and isn’t available to consumers. You can read more about this in post #14 here.
There are also more detailed comments about Leesa in post #2 here and the rest of the topic.
At the moment all of the “one firmness fits all” mattresses don’t manufacture their own mattresses so they are really “resellers” that purchase the mattress from the manufacturer (which is often a foam fabricator) and then resell it to consumers so they would usually have some additional margins or “middlemen” built in to the cost of their mattresses compared to true “factory direct manufacturers” which purchase the raw materials and then manufacture their own mattresses at their own factory.
Phoenix