Hi cher333,
The first thing I would suggest is to read post #10 here which has a step by step process that can help you avoid most of the worst choices (like buying a major brands) that most people make and help you connect with the better manufacturers and sleep shops where you can get more accurate information about a matress you are considering and end up with a much higher quality and value mattress.
Post #6 here also has lots more information and links about memory foam and sleeping temperature so that you don’t get unduly drawn into the marketing hype or “story” that surrounds sleeping cool in every part of the industry these days. There is a lot of misinformation out there that is drawing people in to spending a great deal of money on a “story” rather than a mattress.
Some of your better options that I’m aware of within reasonable driving distance are in post #4 here.
Phoenix