Most listings are in the $30's per square foot per year. The Diamond Bar region is experiencing a decrease in rates. In the last 3 months, the median rate fell $2 per sqft per year. That's a 7% decrease in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Diamond Bar submarket has smaller rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 4 listings have been made available, which means spaces most likley are 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.
Even though the median size is 13,000 sqft, there are still 0 office spaces below 2,000 sqft. Most properties in this area are around 2 stories. Most buildings in this market were built in 1988 and are Class B.