The typical asking rate per listing is in the $20's per square foot per year. The Pomona submarket is going through a an increase in rates. In the last 3 months, the median rate went up $8 per sqft per year. That's a 36% increase in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Pomona submarket has less expensive rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 16 listings have been listed, which means spaces are probably leasing quickly. 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 1,600 sqft. Most buildings in this region are approximately 2 stories. Most buildings in this area were built in 1983 and are Class B.