A friend recommended the Collectibles Insurance Agency, Inc. They specialize in insurance for collectors and from what I have seen, they are very reasonable. I'm preparing to send my application in, so obviously I don't have any experience with them, but I'm told they have a good reputation. Here is the contact info:

Collectibles Insurance Agency, INC
Box 1200
Westminster, MD 21158-0299
Telephone: 888-837-9537
Website: www.collectinsure.com

If anybody has any information, either positive or negative, about them, I would appreciate hearing from you.