The typical asking rate per listing is in the $20's per square foot per year. The Riverside region is experiencing a decline in rates. In the last 3 months, the median rate decreased $4 per sqft per year. That's a 14% decrease in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Riverside submarket has less expensive rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 50 listings have been made available, so you'll want to check back regularly for new listings. About 2% of the available space in the Riverside are subleases, so you will probably have to consider a longer term lease. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,800 sqft. Most buildings in this market are close to 2 floors. Most buildings in this area were built in 1989 and are Class C.