How much does value change when a Grulla is an Orvis branded gun?
As stated above unless the gun has some extra finish or features there is no premium. LGS had couple of second-hand SLEs made for Griffin & Howe by either Arrieta or Grulla and they sold for same as regular offering from company with same level of finish. The Orvis-Beretta Fowler brought in extra $500 over the 426 , Black Onyx or whatever they were called because it had extra action polish, and straight grip stock made of better grade wood.