There's an community in nothern Virginia called EcoVillage which is a mix of suburban-style houses and a green rural community. I visited the village a couple of years ago and was surprised to see rolling grassy hills with houses nestled in them, fairly close to regular suburban areas. It was obviously in early stages of development, with many houses still being built.
The literature says "the community is nestled on 180 organically managed acres of beautiful rolling hills north of Leesburg". Lot prices average $123,000, which includes your lot, use of the shared acreage, and use of the Common House (EcoVillage's own community center). The construction cost of one's house depends on the size, amenities, and finishes that are selected. However, home prices (including the lot) are averaging in the low $400,000s. :: EcoVillage