How much room do you have for your proposed sauna? There are two person saunas that run about four feet square and are very efficient with quick heat times. How many people will be using the sauna at the same time? This will obviously help determine the size of your sauna. If you are thinking of adding one to your pool area next to the hot tub, there are larger models available or you can build a custom sauna to meet your exact needs.
And when you move, will you want to take it with you? There are portable saunas that you can just plug in wherever you are. Some units are on rollers, and others can be folded and put away when you are done, and don't require any special wiring. All the portable saunas are infrared saunas. Some allow you to climb in a zip bag with the exception of your head and lie down for a relaxing quick nap.