They still exist?! Cal Spa made one for years as did Catalina and few others. They had lots of problems including shell cracks and covers.
If that is the look your going for here is an idea; select whatever protable spa you like that fits your needs best and either rock around it or there are a couple of artificial stone manufactures that make removable surrounds to go around the spa and make it look like a rock spa. I will try and do some research when I'm back tonight and paste the site.
