I own a 10 bbl brewery (www.yellowhammerbrewery.com) and what it takes is a lot of time and money. Architecs, lawyers, graphoc designers, blood sweat and tears. And kegs. YUou need a lot of those.
It can certainly be done and it can be done on a budget but to really make anything worthwhile you are going to need to spend over 100K, and reality much mroe than that. The point of opening a brewery is to open a sucessful business. You establish a brand and produce a product that people consume. It's hell of a lot of work, but it is also awesome and has great rewards.
As far as "selling a few kegs", aside from the legality issues and license expense (I think we pay the ABC $1000 per year for the priviledge to sell beer) my only question is .... why? You will not ever be monetarilly compensated on a 10 gallon system and in the end if you are brewing for 6-8 hours to sell a couple kegs you will basically be paying to sell your own beer. Doesn;t make sense to me one bit. If it is just about the gratification of people enjoying your beer you can do that far easier on the homebrew level.
As someone who seriously wanted to go the nano route I am so glad to hear people with some experience give advice like this! The real reason I wanted to open a brewery is for the personal satisfaction of people enjoying my beer. You are right it IS far easier to do on the homebrew level and with a lot less headaches.
Obviously I can't sell my beer....but that doesn't mean I don't have a brewery!! We have a website, FB page, sell t-shirts and stickers, pour at beer festivals and private events, etc....I often wonder how many people think we are a commercial brewery
In fact somebody the other day said it is an "underground brewery" which is cool...though I was quick to point out that we don't sell our beer. We get everything out of it that a nanobrewery would ( personal satisfaction, name recognition, etc...) but without all or most of the headaches ( fees/permits, licensing/zoning, negative cashflow, expectations).