Silent, check out your local hardware store (Lowe's, Home Depot, etc). They sometimes carry dessicant containers meant for people to place in their basement, storage closets and other such places. My mother-in-law has them in her storage area which is in her garage. It comes in a plastic container about half as tall as a peanut butter jar. You just unscrew the lid and place it in the room.
Go to the hardware store's web site and do a search for "dessicant". Look for something like "DampRid" or "Keep It Dry". I'm guessing that, in the store, you'll find them by where they sell things like dehumidifiers and other such items.
Hope that helps,
Eric
PS. On a side thought, I've never tried this before but I wonder if a local pharmacy will give you a small handful of dessicant packets or capsules if you just ask for them. I remember going to Sam's Club and asking for those little black film containers in the photo development area. I explained to the lady that I use them for mixing paints since I'm a model builder. She gave me a shopping bag full of them!