I built a super cheap "traditional" dry sauna. It's basically an electric burner, a pot to increase surface area and humidity, a 25 foot roll of thermal foil, and a sleeping bag as the ceiling. I disassembled the burner, removed all the plastic pieces, and short circuited the safety cutoff. It's jank AF, but in the end less than 100$. AFAIK there aren't any dry saunas under $1000 - the heater alone is ~$200. Mine is also portable, so it's in the garage in summer and in the laundry room in winter. There are portable infrared saunas for ~$100, but most studies are on the "dry" type. I rubber band a block of ice to my phone and do my reading/social media in there, so the time cost is reduced. It's pitch black in there, so I have a very bright night light. No problems with air circulation - it doesn't get stuffy, even when I throw a dash of water in the pot. https://i.imgur.com/Lml7Vms.jpg

2 years in and I haven't burned down the house... yet. I've since added more ceramic around the pot so burning myself would be very difficult.

(Reference to my post from the last time this article was posted on HN: https://news.ycombinator.com/item?id=28495062 )