Hi SallyS,
The mattress you are looking at looks like a privately labeled version of the Naturepedic EOS standard. It uses high quality, durable, and “safe” materials and components and there are no weak links in the design.
Naturepedic has a retail finder on their site that you can use to search for other retailers in your area that carry them.
Other than that it would be a matter of looking at websites or talking to local retailers on the list here to find out if they carry mattresses that use similar components (pocket coil/latex hybrids or a pocket coil with a microcoil comfort layer). I would keep in mind that other mattresses that use similar components can be very different in terms of PPP and how they will feel to you.
There are some innerspring/latex options listed in post #2 here.
Pocket coil mattresses that use a microcoil comfort layer are a little more difficult to find but Berkeley Ergonomics makes a mattress with similar components as well.
Phoenix