On average, listings lease in the $20's per square foot per year. The Riverside region is seeing a decline in rates. In the last 3 months, the median rate decreased $2 per sqft per year. That's a 6% decrease in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Riverside region has lower rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 53 listings have been made available, so you'll want to check back regularly for new listings. 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 area are close to 2 stories. Most buildings in this market were built in 1989 and are Class C.