The typical asking rate per listing is in the $40's per square foot per year. The Castro Valley submarket is going through a a boost in rates. In the last 3 months, the median rate increased $44 per sqft per year.
Compared to the rest of the East Bay market, the Castro Valley submarket has more expensive rates, and you'll need to pay a premium to be in this hot submarket.
In the last 90 days, 0 listings have come on the market, which means new availabilities most likley are going fast. You'll want to be prepared to make an offer immediately. About Inf% of the listings in the Castro Valley are subleases, so you might be able to find a shorter term or below market rent. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,400 sqft. Most buildings in this market are close to 1 floors. Most buildings in this area were built in 1982.