Little houses in Sonoma can cost anywhere between $35,000 to $80,000. These are already built houses that are either laid in foundation or on wheels. These houses are fully customized. However, if you want to hire a builder to build your own little house, you can expect to spend around $10,000 to $30,000 in materials and another $2,000 to $5,000 for the labor cost of your project. If you do not have a building plan, you can purchase one for around $750 to $800. Most homeowners tend to use recyclable materials for their little houses in Sonoma. While it is environment-friendly, it is highly advisable to use salvage materials that are still in good condition and will not cause any problem in the long run. It is best if you purchase brand new materials that can have an effect on your energy consumption like insulating materials.