To protect lens and camera from humidity in moist weather, is it advisable to keep it inside a electronic desiccator box (dry cabinet)? Is it just a fancy, overpriced iron safe or does it really work? Who all are the reliable players in this market?
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.
When I went to the Amazon jungle (extremely humid) I was advised, before the trip, to collect those little desiccant packets that come with so many products that you purchase, like electronics or computers, for example. Then as a different answer in this thread suggests, put your camera and the packets into a reasonably airtight box or bag. Those bags that kayakers use to keep things dry (they are actually called "dry bags") work well, both for this purpose and just when you are in the [wet] field.