I've had a policy for a few years that I got through Flather and Perkins (rep: Ann Phenix, 800-422-8889, email
[email protected]) who I gather do a lot of policies for artists.
They arranged for a commercial policy through The Hartford that covers a number of different things for my art business. Among them, it insures my work in transit and when it's on display outside of my studio. I don't know if the premiums and deductibles will be to your liking but they probably have a number of different options that would be worth checking out.