I have just now come across machines called
halogenerators (aka:
dry saline generators) that are designed to produce the salty air of a salt cave. Examples of halogenerators are shown
here and
here. The price of some of these machines runs into $thousands. Yet my
ultrasonic humidifier method for creating salty air costs just the price of the humidifier —
around $20 or $30! I also came across
this UK company selling 60 minute sessions sitting in their salt room for £35.
By comparison, the ultrasonic humidifier approach to halogeneration is a much cheaper and much more straightforward means of saline air generation, and one that can be used at leisure in your own home.
Edit: actually, I just found
this $85 product which is a purpose-built ultrasonic halogenerator for halotherapy. This product appears to be basically just an ordinary ultrasonic humidifier in which you place a saline solution. So it's no different to the method I detailed above, involving placing a saline solution into regular $20 ultrasonic humidifier in order to create salt filled air.