Consider this: Our annual ABC license that allows us to sell beer is $1,000. Your local regulations may be different, I dunno, but you are going to really have to work hard to make any kind of profit on a 5-10 gallon system.Yeah, but WA is a pretty brewery friendly state . . .
Microbrewery's license — Fee.
(1) There shall be a license for microbreweries; fee to be one hundred dollars for production of less than sixty thousand barrels of malt liquor, including strong beer, per year.
Well, that's just plum reasonable!
My main concern when people start to take homebrew to the masses is still the fact that it is an awful lot of work for such a small return. If you are brewing on a 5 - 10 gal system you will end up brewing more for bars and pubs than for yourself and you still won't be making any money and you will end up working basically for free. The most important part about homebrewing for me was having good, fresh beer on tap all the time - for ME! If you start brewing for local establishments you will not have very much beer around the house. What is worse, you will most likely have to pay to drink your own beer.
Another think to consider: pubs and restaurants start to get pissed when you can't keep up with demand. Especially if you are taking up tap space. If you can;t keep a keg on that tap most places are going to bump you for someone more reliable. An empty tap costs an establishment money.
Not trying to rain on any parades, just trying to point out a few facts folks may not have thought of. Brewing beer is a lot of work, for sure.