This is starting to remind me of the situation over on the Steel Guitar Forum - There were two machinist guys who's jobs either were or were about to be munched by this little economic depression we got going on. And being machinists, they each had a home rig too - I guess when a machinist gets home from a hard day of machining, nothing relaxes him better than going out to the garage for a little... machining! Anyway, so they posted up on the forum "Will make steel guitar parts! Clamp-on drink holders, amp chassis, car parts, ARRGH!" or words to that effect. They both got swamped, and had to stop taking orders after a month or to catch up with the demand. Leaving them to wonder "Why did I work for The Man for THIRTY YEARS when I coulda been out in the garage making money..." or words to that effect.
If you have a useful product, it's a wide open field... there sure is a whole load of guitarists out there. There are a few little things like the IRS, business zoning etc. to consider - I doubt even half the "businesses" on Ebay are licensed, approved, inspected, PAYING TAXES.... One of the cleverer deregulation strategies of the Bush->Clinton->Bush years was to not change the laws on the book - but simply un-fund OSHA, the FDA & the IRS. When you don't hire any inspectors, nobody gets inspected! It may hold for quite some years, but the IRS (especially) are some greedy fucks.