Hi Redsaffron,
If you are looking for an online latex mattress then post #21 here includes the members of this site which sell latex mattresses online. They include a wide range of different types of latex, designs, features, options and price ranges.
Posts #3 and #4 here also include some lower budget latex and latex hybrid choices if that’s what you are most interested in.
If you are looking specifically for synthetic continuous pour Dunlop made by Mountaintop Foam then the Brooklyn Bedding Tri-Comfort here is the only other option I know of in a good price range that reflects the much lower cost of the synthetic latex. Nest Bedding here also sells the continuous pour sythetic latex from Mountaintop but they are in a higher price range.
Phoenix