Hi 1ch1ban,
You are getting some “partially correct” information which can be more misleading than anything else.
All manufacturers make some good quality and some low quality memory foam so who makes the foam is not indicative of quality. You can see the criteria I use for memory foam mattresses in post #10 here.
The polymer density of memory foam is the most important part of its relative quality and durability. You are also correct about memory foam “fillers” but Chinese foam comes in both good and bad quality just like American foams. Cheap Chinese foams are just that … cheap and low quality. There are also good quality Chinese foams however which can be good value. One of the criteria I use is whether a memory foam is CertiPur certified (which is especially important to know if the foam is Chinese) and there are at least 3 Chinese foam producers which are CertiPur certified just like many (but not all) of the American foam producers.
You can read more information in post #9 here about the different qualities of memory foam that are affected by different chemical formulations and manufacturing methods that are independent of density but the unfilled polymer density of memory foam is the single most important part of its durability.
The Tempur Cloud line actually uses a combination of 4 and 5.3 lb memory foams … not 3 lb. The base layer is 2.2 lb polyfoam. The 4 lb density is less durable than 5 lb memory foam but it also has qualities which some people prefer in terms of faster response, higher breathability, and a softer feel which is the tradeoff for the lower durability. So the specs are worse in terms of density and durability (which is why I would be careful about buying a Cloud if I was over 200 lbs or so) but they can still be a preference for many people because of the other qualities of the lower density foam. The durability of a material can also depend on many other factors including where in the mattress the layer is, on the thickness of the layers, and what is above and below it.
You are correct about this and SleepEz only carries the one “traditional” memory foam model which is a fairly basic or “standard” layering with 3" of 5 lb memory foam over a good quality base layer although they also offer a layer of memory foam in their latex mattresses for customers who want it. They will sell their memory foam mattress on request of course and there may be more that buy it in person at their bricks and mortar outlet but their focus is on latex in their online sales.
You also have several other options that are similar or perhaps even better value (depending on how you define value) available to you that specialize in memory foam mattresses and are in the list I posted previously.
Phoenix