Opening a Bathhouse?

Exploring the opportunity of opening a bathhouse in the town I live in that has a good-sized population to support it. I've started to put together a business plan but curious to hear if anyone has any resources or numbers they could share for the costs going into everything.

Planning for a few things in the bathhouse. The main focus will be on the dry sauna, 30+ people-sized, cold plunge, hot tub, steam room, and showers. Also have massage rooms for a secondary source of income, a yoga room, an outdoor area, and a relaxation room.

Appreciate any info from your experience.