Source Naturals has an HGH precursor supplement called HGH Surge.
Source Naturals :: HGH Surge™
This company has won many accolades for making the highest quality naturally derived formulas for a wide array of supplements. I've been taking their multiple vitamin on and off for years.
They have other amino products too.
I'm thinking of trying the HGH Surge after scanning this thread today.
I don't think you can buy direct from the company, but they link to retailers and you can find others with a Google search for their products.