The typical asking rate per listing is in the $20's per square foot per year. The Corona region is experiencing a an increase in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 3% increase in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Corona submarket has smaller rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 99 listings have been made available, so you'll want to check back regularly for new listings. About 1% of the available space in the Corona are subleases, so you will probably need to consider the implications of signing a direct lease with the building. 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 1,590 sqft. Most properties in this market are around 2 stories. Most buildings in this region were built in 2005 and are Class A.