Hi Moc cock 8,
The first place I would start your research is the tutorial post here which has all the basic information, steps, and guidelines you will need to make the best possible choices.
You can read more of my thoughts about BedinaBox in post #2 here. I would be very cautious with any memory foam mattress that didn’t meet the minimum guidelines listed in post #10 here.
You can also see some of my thoughts about Amerisleep at the end of both post #4 here and post #4 here and a forum search on Amerisleep (you can just click this) will bring up more information about them as well.
There is also a link to a list of some of the better online memory foam retailers and manufacturers I’m aware of in the tutorial post. Neither one you mentioned would be among my first choices.
Some of the better options and possibilities I’m aware of in the Charleston, SC area are listed in post #2 here.
Phoenix