I used to have a rider on my homeowners, and it ran me about $10.00 for every $1000.00 worth of insurance per year. That was with State Farm. I have since purchased a huge gun safe, which is fireproof to a certain degree, heavy (and bolted to a concrete slab), and I also have a home security system. I sleep better with the safe than I did with the insurance. I know they're securely locked up, have a chance of surviving a fire, and I don't have to worry about the insurance company trying to give me half of what I think they're worth should I have a loss. From a liability standpoint, you're probably better off with a safe too. If some teenager were to break into your home, steal one of your guns and shoot his foot off, or worse, I'd hate to have to deal with the potential lawsuits.
Ideally, you should probably have both a rider on your homeowners, and a safe. I suggest at least checking out some of the safes made by Liberty or Browning, and if you can afford it, get one. As for insurance, check around. It's probably like car insurance...some companies just have better rates. Hope I helped.