Fire, theft, flood, invalidism, accidental damage, misuse, act of God...
If your shop is on your house property, it should be protected under your Home Owner's insurance. Check with your insurance broker, find out under what conditions it is, or is not protected, and if there are any limits on the protection of the contents. of it.
For example, MANY home owner's insurance policies will not cover the collect car cost of our cars, but only it's value as a "used car". You're $15,000 Dart might only be worth $750.00 to the insurance company if they do not have a record of it and you do not have Collector Car Coverage. Some home owner's policies will not cover a classic or collector car, at all!
Have a discussion with your insurance agent. Find out what is covered, what you are covered against, how much you are covered for, and what, if anything, needs to be done to be sure ALL of the contents are covered for their replacement value AT LEAST.
This isn't meant to sound condescending, I'm just trying to point out the fact that there are a mountain of variables in insurance policies, at different levels of coverage, and even by company, and region. It costs nothing to find out about YOUR situation.