There are many factors that can affect the cost of building custom garages in Castro Valley. You need to consider the location of the garage, the complexity of the garage design and layout, the size of the garage, the materials needed, and the labor cost. It has been estimated that building Castro Valley custom garages can cost anywhere between $1,200 and $50,000 depending on the factors stated. On average, custom garages in Castro Valley can cost $23,000 with most homeowners spending around $17,800 to $26,300. The design and layout of custom garages in Castro Valley play a major role in the overall cost of the project. The more complicated the design is, the more expensive it can get. If there are a lot of special features and storage added, expect to pay higher than normal.