On average, listings lease in the $30's per square foot per year. The Corona region is experiencing a an increase in rates. In the last 3 months, the median rate went up $0 per sqft per year. That's a 1% increase in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Corona region has lower rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 16 listings have been listed, which means office spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 250% of the office spaces in the Corona are subleases, so you might be able to sign a shorter term by taking over a previous lease. 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 1,600 sqft. Most properties in this market are around 2 floors. Most buildings in this area were built in 2005 and are Class B.