Here's my take (and believe me, I've thought a lot about this topic): WezV is right. Get to 10, and by then your business should start developing naturally. It certainly doesn't hurt to have a plan now, and to aim for it. Think about this: would you pony up 2-3k for a guitar, even if it looked really nice, if you knew the guy had only built that ONE? I'd certainly have reservations, no matter how sweet the work was.
And as many have said in here before, it doesn't make sense to have an idea that you can make a lot of money doing this. Of course you COOOUUULD, but that isn't what you should be aiming at right now.