Hi DeniseChirpich,
Post #1 here has a series of steps and guidelines which along with the information it links to can greatly improve your chances of finding the most suitable mattress with the best possible quality and value in any budget range.
You are also fortunate to be in the San Francisco area which has some great quality/value choices and options available in any budget range. The better ones I know of are listed in post #2 here. You may also find that this thread (especially the later posts) from another forum member with some recent feedback from the San Francisco area may also be useful to you.
Phoenix