If I had to put a value on my stash of material at todays prices, I would have to ball park the value at about 5k, then there's all the tools and thread, probably another 2k and then the machines I'd have to add another 4k.
This subject is a real eye opener, I would guess everyone who has any kind of hobby/craft type business that they run in their home should really sit down with their insurance agent and adjust their insurances.