Hi pickamattress,
I’m guessing you mean the firm Talalay as the comfort layer over the Dunlop (as opposed to using Talalay as the support core)?
In any case … the tutorial post includes this link to a list of the members here that sell online and many of them (including Brooklyn Bedding) sell latex mattresses that use different types of latex with a wide range of designs, features, options, and prices, and many of them allow you to choose the type and firmness of some or all of the layers in the mattress.
Posts #3 and #4 here also includes some of the lower budget latex and latex hybrid mattresses (under $1000 for mattress only in queen) that I’m aware of.
No it’s certainly not critical or in some cases even important to have “all natural” latex. In most cases it would be a preference choice. There is more about the different types and blends of latex in post #6 here.
Phoenix