Purchasing a business?? Do you mean you are purchasing the business itself and the inventory ? The business and the building ?
The business,building, AND the land ?
They would each have different implications. If it was just the business you really wouldn't get anything. If the building or the building and land you would get a value.
Generally what happens is a developer goes in to build a project unless this is totally funded by the county. The developer offers you a price and if you turn it down then the county can pursue and land takeover whereby they perform an appraisal and that's the value you get. The amount you get is usually never what the owner of the property wants. If you won't sell they can condemn and take the property.
If you are within city limits it would be the city if not the county. There are federal laws in relation to taking of property along with state statute laws that define the minute details of each process.
If you were thinking of buying such a business I would have along due diligence period built in to do a lot of research before purchasing. You need to get legal advice and this is NOT legal advice.
Do not make a purchase based on half-truths and rumors. Get the FACTS to make an INFORMED decision.