You should think twice before buying an infrared sauna. Some have even been proven to be faulty and dangerous (See
ESA, Unapproved Infrared Saunas ).
In the traditional heater, the heating elements heat the air and a mass of stones. This allows for a consistent heat and the custom of sprinkling water on the stones, which changes the environment in the sauna dramatically.
The infrared heaters have exposed heating elements, so that the heat radiates directly onto the bather in sort of a one sided fashion. These infrared heaters have a much lower capacity, so the most common complaint is that they fail to attain the heat typical for a genuine sauna, especially on the part of the body turned away from the heater.
You also sacrifice the ability to sprinkle water on the heater, and one must question whether it’s actually healthy to expose one’s self to such direct radiation, or how enjoyable such an experience is, compared to the traditional sauna.
In contrast, the traditional Scandinavian style saunas are centuries old (they were heated with wood before electricity), and their safety and therapeutic efficacy is well established.
Good luck in your quest for the sauna that's right for you!