Hi Chirurgeon,
The first place I would start with your research is post #1 here which has the basic information, steps, and guidelines which can help you make the best possible choices.
Post #12 here also has a list of some of the better online memory foam options I’m aware of. Some of these match the “feel” of some of the Tempurpedic mattresses … some match or better the quality of their materials … and some match the design of their mattresses as well (and some match all three). They all have much better value than the Tempurpedics in common.
Phoenix