hm. ok my calculation was: 100 gallons = 380L. I am selling my beer for $6.50 for 0.4L = 950 beers / month = 950 * $6.50 = $6175. If I am not wrong with this math I do not agree. My plan is just to find a place big enough to produce this amount of beer with room for expansion to maybe 3 times as much. I am NOT planning on selling my beer anywhere else.

I'm sure your math is right, but that's 3 barrels. Per month. I'm assuming you want more than one style on tap so you're talking about brewing roughly 1 bbl batches roughly once a week. The $100 in raw materials is trivial, sure, but how about the 10-20 hours a week in labor? How long will it take to amortize the equipment and other startup costs? Even at steady-state, can you make that little beer for less than you're paying now? My guess would be yes, but not by a whole lot.