Of 56 counties in the Treasure State, Custer County is 11th in terms of its size (3,793 square miles). Custer County is in Southeast Montana. The total value of roughly 1,000 acres of riverfront homes and property recently listed for sale in Montana's Custer County was almost $900,000. Browse all waterfront property for sale in Custer County on the Land Network to find the marina, lakefront and other recreational property that meets your needs, from waterside land perfect as a retirement investment to existing residential waterfront land and property for hunting, fishing and other outdoor-recreation pursuits! The most common type of land for sale by combined acreage in Custer County is house.