I had my bass and all my equipment insured through Merz-Huber, the one ISB recommends and for which you can get a good discount. However, when they raised their minimum to $200/yr (not really a problem) and their deductible to $500 (a problem since I have several items in the $100-500 range), I looked around and found
www.musicpro.com
They have a $100 deductible, and as a bonus cover $5000 (I believe that's the $#) worth of computer equipment as well under the same premium - which was good for me with all my PC stuff. They are not as "professional"- I guess that's the way to put it, as Merz-Huber, and are slower to react to changes, but so far so good, I guess. I don't know anyone personally who has filed a claim with either.