On average, listings lease in the $20's per square foot per year. The El Cajon region is seeing a a rise in rates. In the last 3 months, the median rate rose $10 per sqft per year. That's a 51% increase in rent.
Compared to the rest of the San Diego market, the El Cajon submarket has lower rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 15 listings have been listed, which means office spaces might be leasing quickly. 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 1,300 sqft. Most properties in this area are around 2 stories. Most buildings in this region were built in 1978 and are Class C.