In most climates, a desiccator is unneeded, but in the tropics, in marine locations or any place with extreme humidity, it might be helpful. However, you can make your own for very little.

In an airtight plastic or gasketed metal box, place a container of calcium chloride or similar desiccant. Such chemicals are available in inexpensive closet dryers and as driveway ice melter.

N.B. Calcium chloride (CaCl2) can make dust, more damaging to cameras than water, and it is so hygroscopic that eventually it will absorb enough water to liquefy. Keep the CaCl2 in a porous container e.g. in a cloth bag inside a small plastic box with holes drilled in the lid, with a cellulose sponge underneath the bag. Make sure this inner box won't pop open or come in direct contact with camera components.

The CaCl2 can be regenerated every few weeks by baking above 100oC, as long as it has not liquefied and soaked into the sponge. Keep the desiccator closed whether or not there are items in it.

This desiccator does not rely on external power and should work for months or years, until a new charge of CaCl2 is needed.