I pay $7.60 per year per $1K of covered gear. As with all insurance, rates will vary based on your location.
That again reminds me that I still live in "emerging market" (central Europe, part of EU). I just checked websites of few insurance companies - none of them offers such insurance (at least not as a standard service offered on their web sites). One got quite close with musical instruments but the upper bound was $2k-$2,5k and it didn't include insurance of any damage caused by incorrect handling. The price was 5x higher anyway.
The biggest local retailer offers similar insurance. From my understanding of their terms the insurance can be applied only when buying new equipment directly from the retailer. It can be arranged for one or two years and it cost 8x times more per year. I'm not sure how it works when you want insurance for longer time-frame.
There is still possibility that such insurance is provided by insurance company on-demand but from my experience the cost of any on-demand service will be really high. The cost of the insurance will also be affected by the participation in repair / replacement cost after accident. I can easily imagine something like 10% (or even more with small or none participation) of the equipment cost per year and that would be only insurance of the item for personal usage (no business related lose will be included).