The value of farms, ranches, hunting land and other land for sale in Custer County, Idaho, recently on Land.com was $82 million. This represents nearly 4,000 acres of farms, ranches, hunting land and other land for sale in Custer County. Custer County ranks 32nd in the Gem State for the total acreage of land currently advertised for sale. Mackay had the most land for sale. Economically speaking, Custer County's is largely dependent on mining and mineral extraction-related businesses and services. Custer County is one of the ten biggest counties in Idaho (4,938 square miles). It's located in the Central Idaho region of the state.