Most listings are in the $20's per square foot per year. The Chino region is going through a decline in rates. In the last 3 months, the median rate fell $9 per sqft per year. That's a 27% decline in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Chino region has lower rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 9 listings have been posted online, which means new availabilities are probably going fast. You'll want to be prepared to make an offer immediately. 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 2,000 sqft. Most properties in this market are close to 1 stories. Most buildings in this market were built in 2003 and are Class A.