If you're going to buy a decent sauna you're going to spend $1,000 and up for a decent model. I've had three saunas and the first one I bought which was probably 25 years ago and it cost me about $1,400 and was amazing. I bought two saunas since then and both of them being pieces of crap even though they looked almost identical and they were under $1,000.
These were infrared saunas not wet saunas
The first brand that I had was called healthmate they're still in business and I found them to be extremely reliable.