Just to clarify things before answering Oldfed's question. In spite of everything else I have done in my life I am currently, and for the past 20 years been in the insurance business dealing specifically with Personal Lines Property and Casualty daily.
First is to define "Vacant land". And most of you seem to have a good grasp of this. To qualify as vacant land the plot must have never been developed in any way. Even a single strand wire fence or a tree house that kids built on the property takes it out of the realm of "vacant land".
Truly "vacant land" is automatically covered under your homeowner's policy if it is a standard ISO Form as written by most standard companies. Likewise any cemetery plots which you have an interest in are automatically covered.
If the property has ever been used for any purpose, even farm land that is now fallow, this coverage does not apply, and most standard insurance companies will not insure it. In this case you would need to purchase a CPL policy typically sold by a Surplus Lines or E&S agency. The cost will definitely not be $150 or less a year.
An Umbrella policy is a good idea, everyone should have one. You have to understand something about an Umbrella, and that is they carry a very large deductible. For an Umbrella the "deductible" is referred to as the "Minimum Underlying Coverage Requirement", typically $300,000 or $500,000 for Personal Liability. If you have an exposure which is not covered by primary insurance the Umbrella will not respond until the deductible has been satisfied, if at all. In addition there is a second portion of a claim which you would be responsible, and that is the "Self-insured Retention". The SIR can be as little as $0, but usually $1,000 or more. An Umbrella also will not respond until you have been sued and there has been a judgment against you.
What I am trying to convey is that an Umbrella is not automatic protection against unforeseen liability claims.
