Had been just the double garage 500', dubbed the garagio (I know real original). Just added and bringing online a 300' free standing studio with a cedar deck along the front for spring/summer drying. The business has also absorbed two bedrooms for another 300' for office and staging/photo/packing and shipping.
I will be adding a brick patio 'kiln' area housing a pit, raku and gas kiln and will be adding and additional 200' building, finished out and used initially for stock and inventory.
It does take over the place but wow it saves a fortune when compared to renting 1200-1500 feet of studio space and paying monthly rent, triple net and utilities.
We live in a neighborhood of 1 acre homes sites so we are not much bother to our neighbors. The new kiln area will be about a football field from anyone's house (except ours :-) so I am hoping it will continue to not bother anyone. Most of our firing will remain cone 6 electric so this should work.
I always think of a kiln load costing about $10. $6 for the firing cost in my case and $4 for the element replacement every 100 or so firings. Even if yours is a few bucks more or less electric is the cheapest way to go and once you factor in a kiln load of ware it is pretty cheap on a per piece basis. I do get that in some high cost electric areas you might ant to change the time when you fire somewhat.
I would add that the electrician you call will really impact the cost. When I bought my house I looked and finally found an electrician willing to do work on my house at an hourly rate. He charges $120 for the first hour and $80 an hour after that and EVERYTHING is way cheaper than the job guys. When I added a 9 cubic foot kiln he came out and added a dedicated plug for it and was there for a couple of hours and my bill was a couple hundred bucks. When I had a 2nd patch panel for my generator to plug into to run my house in outages it was a few hundred bucks when two other 'bids' both exceeded $1000 and a third one came in at $3500.
Ya really need to beat up price. there is no reason for an electrician to get what often works out to hundreds and hundreds of dollars an hour.
That's not a particularly small kiln and you are venting harmful gases and they really ought to be vented to the outside. Is there a way to run the vent through the garage but end up outside without the whole door propping routine? At least if the kiln was in the garage it would be crystal clear what was going on, the way you outlined it just sounds like it would be so easy for someone to be working in the garage on something and have no idea that harmful gasses are being piped in.