Most listings are in the $20's per square foot per year. The San Dimas submarket is experiencing a a boost in rates. In the last 3 months, the median rate increased $3 per sqft per year. That's a 13% rise in rent.
Compared to the rest of the Metropolitan Los Angeles market, the San Dimas submarket has smaller rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 25 listings have been listed, which means spaces are probably going fast. You'll want to be prepared to tour spaces as quick as possible. 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 1,730 sqft. Most properties in this region are close to 2 floors. Most buildings in this area were built in 1989 and are Class B.