Most listings are in the $10's per square foot per year. The El Cajon region is going through a decrease in rates. In the last 3 months, the median rate decreased $4 per sqft per year. That's a 19% decrease in rent.
Compared to the rest of the San Diego market, the El Cajon submarket has smaller rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 16 listings have been made available, which means new listings might be going fast. You'll want to be prepared to make an offer immediately. 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 710 sqft. Most buildings in this area are approximately 2 stories. Most buildings in this region were built in 1977 and are Class B.