Hi sleepking,
There is more about the different ways to choose a suitable mattress (either locally or online) that can help you identify and minimize the risks involved with each of them in post #2 here and there is more about the most important parts of the “value” of a mattress purchase in post #13 here that can help you make more meaningful comparisons between mattresses.
The better options or possibilities I’m aware of in the San Francisco region (subject to the “value” guidelines I linked) are listed in post #2 here.
The mattress shopping tutorial also includes two links to lists of many of the better online options I’m aware of (in the optional online step) and post #4 here and posts #3 and #4 here also include some links to some of the better lower budget online options I’m aware of as well.
Phoenix