Im a full time insurance agent as well as a videographer. Like many questions asked on this forum, the answer to your questions depends greatly on many factors. But, to comment briefly, what you need is an "inland marine" policy that protects your equipment anywhere anytime and for "almost" anything. This does not need to be provided by an association or anyone specializing in "wedding videography" insurance (sorry for all the quotation marks). The cost varies on the exposure, type and value of equipment. And of course there is liability insurance, E&O, and much more but, you didnt ask about those. If you would like to discuss this further let me know and I can email you.