What the numbers usually show
A mid-range 2-person cabin (~$1,800) with a new dedicated circuit (~$600) and four 45-minute sessions a week at $0.17/kWh costs roughly $2,700–$3,000 over five years — and electricity is only about $150 of that. The purchase price dominates; running costs are small.
Where the money actually goes
- The cabin (70–80%): the one cost you control most by choosing well.
- Electrical (10–20%): a dedicated 15A or 20A circuit is the single best install upgrade — it prevents nuisance breaker trips.
- Electricity (~5%): even a 1,805W cabin costs well under $1 per session at typical US rates.
- Upkeep (small): seat pads, wood cleaner, and eventually a heater panel — budget ~$30/year.
Compare that with a spa: at $40–$60 per sauna visit, four sessions a week would run $8,000+ a year. A home cabin typically pays for itself in under a year of regular use.