Hi ZenShakti,
Assuming that you are looking at the Los Angeles list, there is only one manufacturer in Covina which is Flexus. The other option in Covina is Dreamland which is a retail store.
As you probably know from your reading, Flexus is one of the members of this site which means that they compete well with the best in the industry in terms of their quality, value, service, and transparency. A forum search on Flexus (you can just click the link) will bring up more information and feedback about them.
Bruce at Dreamland is also knowledgeable and experienced and a forum search on Dreamland (you can also just click the link) will bring up more information and feedback about them as well.
I would be very cautious about using other people’s experiences with any specific mattress as a guideline for what you may do well with because a mattress that is “perfect” for one person may be completely unsuitable for someone else to sleep on (see post #13 here).
Post #13 here also has more about the most important parts of the “value” of a mattress purchase relative to each person.
Phoenix