Compared to the rest of the San Diego market, the El Cajon region has less expensive rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 15 listings have been made available, which means spaces 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,500 sqft. Most buildings in this market are approximately 2 floors. Most buildings in this market were built in 1977 and are Class B.