Hi Craig99,
The Restonic you are looking at has 9" of blended Talalay latex and the top 1.25" is quilting polyfoam 1.2 lb density which is inside the guidelines (around an inch or so) of lower quality materials that I would consider acceptable for use in a quilting layer.
While it may be better quality/value than most mainstream manufacturers … it’s also not in the same value range as many local manufacturers or many online choices. You certainly have other latex options available locally particularly from some of the local manufacturers where value is often better. Of course you would need to test these to see how they compared to the Restonic in terms of PPP (Posture and alignment, Pressure relief, and personal preferences).
If you do choose to include online options in your search then the members here that sell online are listed in post #21 here and many of these also sell latex mattresses. You won’t be able to directly translate your experience on the Restonic mattress into something that will be comparable in terms of PPP because the designs are very different (even though the materials may be the same) but many of the online choices also have mattresses with 9" of latex which would make a good “value comparison” and your experience on the Restonic may be useful to include as part of your conversation when you are talking to them about your layering choice. Many of the online manufacturers have the ability to choose the firmness level of one or more layers when you purchase and many also have the option of re-arranging or exchanging layers if you need to make changes after you have slept on your mattress.
I would probably start with some of the local manufacturers (after talking with them on the phone) and then look at any of the online manufacturers that most interest you as a comparison so you can eiminate the worst options and are making final choices between “all good options”.
Phoenix