I just talked to a woman from CollectInsure.com. She was super nice, and wondered why she's getting so many calls from pinball collectors lately. I sent her this thread.
My quick quote was around 0.7% annually, but that included coverage at my storage unit and burglary coverage. My actual cost will probably be lower since most of my games are at home. They replace using market value, but we didn't discuss how that value is determined in the event of a loss. I look at it this way: it's about the cost of a ColorDMD for peace of mind.