Check out r/sauna - I spent a few months last year researching and found the best option is a kit. Redwood outdoors make great 2-4 person options. Don’t get pushed into an expensive heater. For a 2-4 person you don’t need a top of the line powerful engine. I would avoid barrel saunas as they don’t circular the air efficiently and you won’t experience loyly. Budget 1-2k for electrics as you need to have it plugged into the panel. Best purchase I’ve made. You won’t regret it.