Most listings are in the $10's per square foot per year. The Porterville submarket is experiencing a a boost in rates. In the last 3 months, the median rate went up $16 per sqft per year.
In the last 90 days, 2 listings have been posted online, which means new availabilities are probably leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 50% of the listings in the Porterville 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,000 sqft. Most properties in this region are close to 1 floors. Most buildings in this market were built in 2001 and are Class B.