On average, listings lease in the $30's per square foot per year. The Claremont region is going through a a boost in rates. In the last 3 months, the median rate rose $35 per sqft per year.
Compared to the rest of the Metropolitan Los Angeles market, the Claremont region has smaller rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 1 listings have been made available, which means listings 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.
The standard measurement for office space in this area is around 1,180 sqft. Most buildings in this area are approximately 1 floors. Most buildings in this area were built in 2003 and are Class B.