Andy,
Would you be willing to sell these in kit form as well as a fully finished version? I enjoy the process of building these kind of things, and I am handy with tools. You could include the flat metal plate with a template for the holes and such, cylinder components (tubes, caps nuts, screws etc,), resistors/ capacitors, and any other little parts on the full version. I would buy a couple of those, as I am quite sure I can not afford the whole shebang right now...