Hi AZmook,
Phoenix is one of the best places in the country to buy a great quality and value mattress and several of the manufacturing members of this site are either there or close by.
The first place I would start is post #1 here and the information it links to which will give you the basic information that you need to work more effectively with a manufacturer and make the best possible decisions.
The sleeping temperature of a mattress is determined by many interacting factors (see post #2 here) but any good manufacturer will be able to tell you which of their mattresses will be cooler and why. Connecting with the experts is always much easier than becoming one yourself when it comes to some of the more complex parts of mattress design.
The better options I’m aware of in the Phoenix area are listed in post #4 here.
I wish every area in the country had the kind of local choices available that you do 
Phoenix