HGH from any other source, even from other animals, does not work in humans. HGH must be made using human genetics. The only safe form of HGH is made by splicing human genes into plant cells and then multiplying those cells in a culture media. A protein molecule that large cannot penetrate intact membranes to any significant degree. Most would be wasted if it were used in a nasal spray or orally.
Manufacturing costs are high.
HGH is so expensive that any waste is prohibitively expensive. The technology to make HGH is patented by large pharmaceutical companies and is restricted by law to their use. The HGH molecule loses potency very rapidly when dissolved in solution. The molecule is folded and twisted on itself repeatedly. Activity in the body depends on fragile cross linkages between branches of this very large molecule, which hold it in an exact three-dimensional configuration.