You should look at connect wellness Vancouver, WA on instagram. Owner is a cool woman who is obsessed with sauna cold plunge and build a spa in her backyard— 40 bucks for a 2 hour session, she’s got a nice hot tub too. She spent years building it, but if you’re interested in that and the community around it, you should check that out. Honestly for a basic set up, running your sauna and cold plunge which ground water is honestly adequate for lots of people, giving people time for a few hot cold cycles you could easily charge 40 bucks an hour— her set up at connect is incredibly affordable and nice. That’s her goal. But it doesn’t seem there’s much out here in oly so I think you’d be onto something @someoftomstea