My wife and I have collector's insurance through Hagerty on both her 96 Cobra and my 93 5.0. There are a few requirements:
1. You have to be able to prove that the cars are not your daily drivers. We had to provide proof that we owned two other cars and had to wait a year after we first applied so that they could see how few miles we actually put on the cars.
2. You can drive the car no more than 5,000 miles per year.
3. The car must be stored in an enclosed garage on your property.
4. You must provide a complete set of photos to the company for valuation purposes.
The cool thing about collector's insurance (besides the fact that it's dirt cheap) is that it is "agreed value" insurance and you decide what you want to insure your car for. My Fox is valued at $15,000 and the Cobra is at $20,000. If the cars are destroyed, we get checks for that amount, no questions asked. If they are damaged in a collision, they are repaired with those values in mind rather than "book values". With a regular insurance company, my 93 would be totalled if it sustained over $3000 in damage, since it's book value is about $6,000.
In short, if you can get it, it's great. If your car is a toy, go for it. If you're thinking about it for your daily driver, forget it.