Here is a general listing, with photos, and sometimes prices. Here is the most advanced "tourist submarine" available. You can buy this "acrylic viewport globe" — modeled by an Italian designer — for only a few million. Nor should you ignore this aquatic home, which remains unpriced and perhaps does not yet exist. Here is evidence that the company is for real; see here also. The film industry is one of their customers. Here is their rationale for price discrimination.
Many thanks to Catherine for the pointer.