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

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.