I looked into insurance for a couple past events. What I found out was this:1. FIgure out why you think you need insurance. are you worried about covering the re-enactors? if they have their own insurance, then you dont need it.
are you worried about covering losses to the site? the siteowner should have homeowners insurance or their own larger policy that should cover losses (and homeowner insurance has VERY deep pockets)
are you worried about members of the public getting hurt? again, they should have thier own policy for most stuff. You dont have to sign a waiver to go to the County Fair, for example, but the fairgrounds has their own really big insurance policy. The folks putting on the goat show dont have their own policy, being covered under the umbrella of the sites own policy.
Think about what could happen. Joe re-enactor accidentally chops his foot off with a pike. His insurance doesnt want to pay for this, and so looks for someone else to pay.
If you took out a special insurance policy, it could be said that you KNEW that something could happen, ie admitting liablility...and there's a nice deep pocket for Joe's insurance to go digging in.
Now, some sites REQUIRE that you have auxilliary insurance. This is a big reason we tend to tag along on SCA events....they have a big fat insurance rider and we dont have to worry about it.
hope this helps some...dont forget that every state is different (ie in Washington, a waiver doesnt mean squat, ie you cant sign away your right to sue).
-_AM