Propane?
Ice?
Water?
DME for starter?
Bottle caps?
Priming sugar?
Propane - Not 100% sure, but it costs me approximately $10 for a 20lb tank and I believe I get about 6-7 5.5-10 gallon batches. Let's assume 5.5 gallon batches and it costs $1.42 per batch.
Ice - None. Plate chiller
Water - $3.50 for 10 gallons of Reverse Osmosis. I don't count the water I use from my hose for the chiller since it's negligible.
DME - I typically use dry yeast with no starter
Bottle Caps - None, I keg. When I do bottle, I have the swing tops and don't use caps.
Priming sugar - I force carbonate, which then begs the question of how much C02 costs.
C02 - I haven't filled my 10 lb tank in almost a year. Not sure what it costs per batch, but negligible.
Electric brewing saves a few bucks - propane isn't free. You guys aren't including that cost I see. It's about $1 of electricity to brew a 10g batch. That's what I do.
Putting together a heat stick right now to switch from propane (Or to augment the propane).
If you chill with ice, you need to include that. I pull water from my pool for my plate chiller, then return to pool: net use zero.
That's pretty damn cool. Are you using pumps? If so, how much does the electricity cost for those pumps. Just Kidding

You'll get a headache thinking about all of this (Unless you're a brewery who needs to know).
Then I toss the carboys into my large keezer to get them the rest of the way to pitching temps. No ice, no water.
Same here
I don't use DME for starters. Table sugar & olive oil. I know what you're thinking. Just don't knock it until you've done it for a year or two. I haven't had any kind of extract in my house for at least a year.
I'd like to try olive oil just for the hell of it, but haven't had the balls yet. Glad to hear you've had success.
Kegging can save some money. CO2 isn't free, but I have a 20# tank that I've been using for about 9 months and honestly it doesn't seem like I've used much of it all all. I think it is less than $20 to fill.
Same here. As I said, I think it's ridiculously minimal in cost.