[Phlogiston]

Well, the one I pictured above still has the Ingraham tag on the back. So it goes to reason that those cabinets were made by them. Several of the Emerson radios of that time came with cabinets mad by that company.

The answer to the 2nd part of your question is like what make a Walton(s) so valuable. Some people will pay more for them. So much so that people often claim that a cabinet is made by Ingraham when it is not. Personally, I don't know why.