Hi Supravista,
Unfortunately when cost is the main consideration in a purchase or you are dealing with a supplier that is part of what I call the “race to the bottom” then you will often get what you pay for … or less. You can read more about Foam Factory / Foam by Mail / FBM (or their other websites) in this thread (I would make sure you read the first 16 posts).
In addition to this … a topper choice can be difficult because the same topper will feel and perform differently depending on the person and the mattress you are using it on because how a mattress/topper feels and performs depends as much on the body type, sleeping style, and subjective preferences of the person and the design of the mattress you are using it on as the topper itself.
In the case of memory foam it can also be particularly tricky because there are hundreds of types of memory foams that each have a different type of feel, performance, and response, even if they are the same density (see post #9 here and post #8 here) and if the density includes any fillers then it also may not be a reliable indicator of the quality or durability of the foam.
When you can’t test a mattress/topper combination in person before you make a purchase then post #2 here and the posts it links to includes some information, guidelines, and sources that you can use that may be helpful in choosing a topper that is the “best for you” and your individual circumstances.
The knowledge and experience of who you deal with and the guidance they can give you, the accuracy of their descriptions about their products, and any return or exchange policies they offer, can all be among the most important parts of a successful topper purchase.
Phoenix