“First, you must remember to reuse the existing infrastructure as much as possible, it brings the cost of connecting the utilities way down. Disused train stations are a great example; you can also try town halls and museums; and you may experiment with unused mall sections, but from my experience, it's better to use a public space than a private one.”
“Why?”
“The mall owners can get really twitchy if they can't profit off those square feet.”
“I see. So, public underused spaces with intact utilities, you say?”
“That's right. Oh, and remember to keep all your invoices under $3,000.”
“Why that?”
“Funny you should ask, I clearly remember it being really important back in my time, but now that I think more of it, I guess it's just a habit I picked up.”
Given the nature of what he was building, I assume he bypassed various permits, inspections, code, etc.
Suppose he built to code, without having permits or inspections. What do you estimate the cost to be?
The code probably says this room can't be in that building, so you'd probably need to level the entire train station building and start over. $10M?
Something like that, in an existing backyard shed with pre-run plumbing + electricty with no permits? That'd cost roughly what he paid. I didn't see any obvious code violations in the picture, except probably ADA stuff due to it being too small for wheelchairs.