In the first half of 2010, we brewed 6 batches, 612 (12 ounce beers) at an average cost of $0.53 a bottle. It has been a period of varied results. We have increased our average efficiency from the low sixties into the mid 80's from January to July, and we will be able to reduce consumption of grains as a result. We also have had equipment problems that have held our bottle yield down and our per bottle costs up. Our last beer, watermelon wheat yielded 116 bottles at 85% efficiency ($0.35 per bottle for a 5.7% ABV for a lowly hopped beer). The beer was supposed to be a 5.0% beer, but we had a better efficiency, and if we watered it down to that, would have been producing at almost $0.25 per beer). Our all malt blonde ale was 82% efficiency, but we only yielded 68 bottles because of problems with the boil kettle. We lost at least two gallons (almost a full case). So, while this all averages out, we would be below 50 cents a bottle.
All of that being said, we didn't brew as much as I would have liked, but once a month is respectable. The next six months should have us fixing our process problems. If we get six more brews in this year, I would expect costs to drop and bottle yields to go up. If I can average 80+% efficiency and bottle runs averaging 110 for 12 gallon batches, I would be happy. It would make our average cost about $0.45 depending on what we brew (we don't brew a lot of big or hoppy beers).