Of 21 counties in the Garden State, Mercer County ranks 16th in terms of size (228 square miles). Mercer County is in Central New Jersey. A recent survey of Land Network data records about 1,000 acres of farms for sale in New Jersey's Mercer County, which is valued at a combined $5 million. Browse all Mercer County farms for sale on the Land Network to find the farm, cattle operation, hobby farm or other farm property that's right for your future commercial or lifestyle needs. The most common type of land for sale by combined acreage in Mercer County is residential property.