Hi buylow,
I’m not sure why you would be looking online when there are so many good options in the Phoenix area but to answer your question …
Usmemoryfoam is in the Absolute Comfort On Sale group of companies and sells two of their mattresses.
They are a little less expensive apparently because they don’t include shipping in their prices while the other sites do.
There are a few good online memory foam options in post #12 here as well.
Phoenix