Hi sirenenebula and welcome to the Mattress Underground 
Unfortunately, with all the turmoil and changes in the business world over the last few years, we can no longer provide geographic listings for retailers and manufacturers. The link you refer to, in the post reply for Organic/Natural latex mattress in Tampa, FL is 10 years old, so any info would likely be outdated in any case. You can do a search for Tampa and sort by most recent - there are a few posts in the last couple years referring to Tampa. We also have the Mattress Shopping Tutorial on how to identify a good mattress manufacturer or retailer, if you have not already read it.
Many of the Trusted Members of the site ship across the U.S.; GhostBed, Nest Bedding and My Green Mattress have partnered with stores like Target, Macy’s, Lowe’s and Costco in some regions; and Fox Mattress though several hours drive for you over in Volusia County, custom builds beds off all types at a variety of price points, including many latex solutions, so it may be worth a call and a visit if possible for you.
As far as best quality foam layers…first you can take a look at our Mattress Specifications You Need To Know as well as the Mattress Durability Guidelines, to get an idea of what to look for and the durability of specific materials over time.
Any mattress you choose will be based on your Stats (height, BMI, sleeping position(s) and any underlying health conditions) and your PPP (Posture & alignment, Pressure relief, and Personal preferences)
Also, is there a place where I can copy or download best quality foam, layers etc., so when I go look at brands I can ask the right questions or when buying online I know what to look for.
I am guessing you meant latex, in which case any good manufacturer will have good quality latex, you just need to find the correct firmness level…and decide whether you want Talalay, which is considered a ‘bouncier’ latex rubber as compared to Dunlop latex(like the difference brethren angel food cake and pound cake); but if you are considering other foams, for non latex foams, we generally suggest any foam in a potential mattress has no more than an inch or so of lower grade foams (for memory foam no lower than 4 lbs/cuft for normal range weights, and 5lbs/cuft for higher range weights) and if polyfoam is used, with at least 1.8 lbs/cuft density, just to ensure you have support. We advise avoiding any foam mattresses which do not specify the materials used, of their density, as this can indicate a mattress has foam of insufficient density which can cause premature breakdown of the foam causing ‘valleys’ and ‘peaks’ which can cause aches pains and even alignment issues, as well as being almost impossible to assess for their support and suitability for any given sleeper.
If you find any specific mattresses you are interested in, and provide your Stats and PPP, we can possibly comment on its’ support and durability for your sleep profile.
~ Basilio