I have insurance on the contents of my home but this covers only $300 worth of "cash" (and my deductible is $500), so if someone were to steal my whole collection, I would get the sum of $300. According to my policy, coin collections are protected up to $300 per item, but no mention is made of paper money collections, so I'm pretty sure my insurance company would simply consider this "cash".
Buying extra insurance to cover my paper money collection would have been too expensive, so I just rented a safety deposit box. I get the employee rate as I work for a bank, but the regular rate for a box 5 inches high by 5 inches wide by 24 inches long is $80 per YEAR plus GST - pretty good if you ask me. And you can "visit" your notes as often as you wish (but if you get the urge outside of banking hours, you can look at scans of your notes until you can see them in person).
By the way, I've seen other posts saying that packets of silica should be used to protect your notes from mildew when stored in a safe (in one's house, I assume). Would you also need to be concerned about moisture/mildew affecting your notes stored in a safety deposit box? The environment in my bank's safety depost box area doesn't seem that much different than my own home, except the SDB area is cooler than my home (which is probably a GOOD thing?).