I actually have a spreadsheet with all of my costs so far. I can't post it on here without it becoming a jumbled mess. But here are some of the important numbers.
Total Equipment: $429
Total Batches so far: 13 (all 5 gallons)
Price per batch in ingredients: $333 or $5.12 per gallon or ~$.51 cents per bottle
Price per batch with Equip factored in: $762 or $11.72 per gallon or ~$1.17 per bottle
Difference compared to commercial (assume $10 six packs): $16.67 dollars per gallon or $1.67 per bottle
Thus so far I have saved $4.94 per gallon, or $.49 per bottle for a total of $321.33 in savings on 65 gallons of beer.
Something to also note, my first 8 batches were extract which was much more expensive. Switching to all grain I went from an average of $.61 per bottle to $.35 per bottle. Or, $6.13 per gallon to $3.52 per gallon.
Also note that I worked very hard to get my equipment as cheap as possible. I have 3 buckets, 3 carboys, 3 kegs, all necessary tubing (regulator, etc), a 7 gallon pot, 5 gallon pot, DIY 50 quart mash tun, wine thief, auto siphon, hydrometer, DIY copper IC, funnels, air locks, air stones, air pumps, 88 flip top bottles, 50+ normal bottles, brew paddle.. And I think thats it.
I haven't been brewing huge beers so far, just some APAs, an IPA, 2 Browns, a Cream, an American Stout, an Irish red, and two milds.
These are some exact numbers, but I don't really think it answers the question better than "it depends". Because although these are my numbers, I am sure others' will be much different. If I didn't build things myself my equipment costs would be higher. If I brewed larger beers my ingredient costs would be higher, etc...
Equipment can cost as low as $100 to start, and go as high as you'd like to spend. Ingredients can run a low as $10 or so a batch, to $100+. Everything can vary wildly.
I hope my numbers helped.
Chris