I got a quote for $306 a year for a $4500 bike, and a $300 deductible. Just to give people an idea of cost.
Now get your calculator out and you'll see it's not really worth it unless you have bikes stolen or crashed a lot, also the quote they gave you is an average, unless you filled out the entire form and got a call from a rep that price will change.
I don't know about you, but I haven't crashed a bike since 1984 that resulted in damage, and never had one stolen, and I think that happens to more people than not. So if I purchased that insurance in 84 and kept it all those years I would have paid $9180 for the insurance, I could have bought two of your bikes and had money left over! The other bad thing is technology is changing and inflation goes up, so in order for a bike that was purchased 30 years ago made of lugged steel will that mean they will let me buy a custom steel lugged bike? No, because I only paid $1,200 for in 84 and that's all they would have insured it for, they say that too...they only pay the insured value the bike was insured for at the time the policy was purchased, little tough finding a Reynolds 531 CS lugged steel bike with high end Suntour components on it for that money.
It's a much better deal to have a bike added to a homeowners or renters insurance policy under a floater (rider), but some insurance companies don't have that for bikes so check with your agent. The bike will be insured for appraised value that any LBS can do, there's no deductible, but most insurance companies are in the $175 dollar average range for a bicycle floater. JTD's $38 is the cheapest I've ever heard of.