Hi Lude,
While I’m not Kopavi … post #4 here has a list of sources for various types of materials and Sleep Like a Bear (AKA SLAB) sells all the different ILD’s of Talalay including 14 ILD. The Pure latex bliss toppers are also 14 - 15 ILD (depending on the type) and these are available at many retailers of the PLB mattresses (see their retail outlet finder here which would give you the ones that were closest to the border in Washington state) but they can be significantly more.
Phoenix