Hi MrsPeterson0303,
They are Chinese foams (with the possible exception of memory foam solutions) and none of them that I can see are CertiPur certified (and that or at the very minimum known good quality North American manufactured foam would be one of my criteria) and they also don’t list the density of their base layers. You can see a little more about why CertiPur or reputable certifications (unlike PurGreen) can be important in post #12 here.
All of these are involved in what I call a “race to the bottom” where they find the cheapest offshore (or worse) sources that they can and will often either mislabel them or will use foams that have fillers to create the density that they list (see here) which means that they will not only be less durable based on the real polymer density of the foam … but the filler can reduce durability as well. In other words they are often a “false” density and not what is called the polymer density or in many cases they are not the density that they claim in the first place.
Good memory foams with good base layers don’t come at these prices.
I also compared their shipping weights to what they should weigh if the density of their foams was accurately described and they were all under weight (either that or they were using very low density/quality base layers). The first one didn’t list a shipping weight but I did the calculation with the memory foam toppers that they sell which do list the shipping weight (which came out underweight). In some cases some online merchants will even calculate their density per 2 cubic pounds instead of per cubic pound.
In any case … these are not the types of merchants that I would seriously consider unless you are looking for a “throwaway” mattress where “the deal” or the price you pay is more important than the long term suitability of a mattress, it’s safety, or its durability.
I also don’t know anything (or at least little because in some cases I’ve connected a few dots about some of them) about the merchants or their “real world” experience, reputation, or storefront and who I buy from is just as important to me as what I buy.
I would be very skeptical of all of the choices you mentioned and would call them “buyer beware”.
If I was looking for a low budget mattress in these price ranges I would consider using a layer of higher quality polyfoam with a good cover from a local foam shop (or even some mattress manufacturers) instead of memory foam.
Or an inexpensive futon (you can see a few sources here)…
Phoenix