The typical asking rate per listing is in the $20's per square foot per year. The Corona submarket is experiencing a a rise in rates. In the last 3 months, the median rate went up $8 per sqft per year. That's a 44% increase in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Corona region has less expensive rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 20 listings have been listed, which means spaces 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,100 sqft. Most properties in this region are around 2 floors. Most buildings in this area were built in 2005 and are Class B.