I would talk to Lee Valley for production first. Like Rockler and Woodcraft they do this sort of thing and pay royalties. Unlike Rockler and Woodcraft-they actually either make it themselves or work with factories who can.
Making a product a winner in the marketplace has a lot more to do with marketing and distribution than it does with the product itself. Read about Tesla and Edison for a classic example.
In today's world getting your product out there as a standalone item is both easier and harder. The internet has leveled the playing field-anyone can set up a website-but it has also made people more wary of gimmicks and fly by night operations-with good reason. If you want to devote yourself to your invention fully then by all means determine how to get it made, commit to an inventory, set up a website and get a booth at every trade show you can. All of those things are more difficult the patent. Otherwise try to get someone else to build it and collect a royalty.
I don't know a whole lot about patents-but I believe you will need to spend between $3 and $5K getting it done. It might be best to contact a reputable patent attorney. I think the mailing yourself a part is bogus but I'm not sure.
Best of luck!