Inflatable hot tubs are truely portable. They set up quickly and are easy to pack back up again and take to a cottage or vacation home. They also can stow away for longer periods of non-use such as over cold winter months.
See the current U.S. Inflatable Hot Tub offerings here:
Inflatable Hot Tubs
The next step up are still plug and play spas but made of acrylic and a spa cabinet. Unlike inflatable spas where you typically sit on the floor, a formed acrylic spa has seats and typically more room. But the acrylic versions require at least 2 people to move and a set of dollies, where the portable unit deflates and stowes in the back of most cars.
It depends on how the hot tub will be used and also the price point. These inflatable tubs start at a few hundred dollars, just keep a vinyl patch kit nearby in case they develop a tear or puncture. Repairing the vinyl is similar to repairing a bike tire or other vinyl repair. An inflatable spa hot tub may not work well in cold winter months as most of them do not have dedicated heaters, but rely on the heat provided by the pump. So they can be considered 3-season hot tubs. Even those that do work in the winter may not hold the temperature for very long when uncovered. If winter hot tubbing is in the forecast, it may be better to select an acrylic version with a built-in heater.
Some acrylic spas even have convertible heaters, so you can start with the 1kw heater at 120v and if you find you are using it more in the winter, you can have an electrician hardwire the convertable ones to 230v and instantly the 1kw heater becomes a 4kw heater with the flip of a dipswitch and the moving of a wire in the electronics pack. (Note that this type of plug and play spa is a convertible one and not all of them are).
In any case, the cost of spa ownership is not as bad as it first appears, especially with an entry-level inflatable hot tub that runs on 120v. These units simply plug into a standard wall outlet with the provided GFCI protected cord. This cord is essential for safe operation of the spa as all electrical devices operating near water must be GFCI protected.
Make sure the spa comes complete with a cover to keep the heat in and to keep out debris and leaves.