Hi domiagnew,
There is more about the most important parts of the value of a mattress purchase in post #13 here but the price of a mattress is only one part of it’s value (and in many cases not the most important part).
The price of a mattress is set by the manufacturer and generally reflects the cost of manufacturing and selling the mattress and of course their margins. It would include the cost of the raw materials, the cost of manufacturing, and the cost of all the options (such as a layer exchange) that are part of the mattress purchase. In most cases the mattresses that are made by the same manufacturer would be in a similar value range in terms of their “raw material” value although the margins are often a little higher in higher price ranges.
The “value” of a mattress purchase on the other hand is something that only a consumer can decide for themselves and would depend on all the parts on all the many parts of their personal value equation that are most important to them. For example if you ended up making the wrong firmness choice and need either a firmer or a softer comfort layer then for you there would be real “value” in having the option to exchange your comfort layer but if your initial choice was a “perfect” match for you in terms of PPP then there would be less value in having the ability to exchange it.
There is more about some of the pros and cons of the mattresses you are considering in post #8 here.
There is more about the different types and blends of latex in post #6 here but outside of some of the other factors that are part of the pricing of a mattress that I mentioned in my previous comments … synthetic Dunlop is a lower cost version of latex than 100% natural Dunlop so it would be a reasonable expectation that the price of a mattress that used it would be lower.
You can read more about the difference between a latex/polyfoam hybrid and an all latex mattress in post #2 here but it’s unlikely that you would find a “close equivalent” with a latex core compared to a polyfoam core. I would also keep in mind that even if the materials in a mattress are the same that two mattresses can be very different if the type and blend of latex, the thickness of the layers, the firmness of the layers, or the types of cover are different.
I don’t keep a record of the mattresses that each of the retailers in the hundreds of lists across the country keep on their floor (it would be more than anyone could keep up with in a constantly changing market) so you will need to either check websites or make some phone calls to see if any of them have any latex/polyfoam hybrids on their floor.
I would also keep in mind that the top 3" to 6" of a mattress (depending on weight, sleeping positions, and sensitivity) will have the biggest effect on how two mattresses compare in terms of how they “feel”.
Phoenix