On average, listings lease in the $20's per square foot per year. The Rancho Cucamonga region is going through a a boost in rates. In the last 3 months, the median rate increased $2 per sqft per year. That's a 12% rise in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Rancho Cucamonga region has less expensive rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 36 listings have been made available, which means new availabilities 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 on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,840 sqft. Most properties in this region are approximately 2 stories. Most buildings in this area were built in 1991 and are Class B.