On average, listings lease in the $30's per square foot per year. The National City submarket is seeing a a rise in rates. In the last 3 months, the median rate increased $31 per sqft per year.
Compared to the rest of the San Diego market, the National City submarket has less expensive rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 5 listings have been made available, which means new availabilities might be going fast. You'll want to be prepared to make an offer immediately. About 320% of the available space in the National City are subleases, so you might be able to sign a shorter term by taking over a previous lease. 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 1,010 sqft. Most properties in this market are approximately 2 floors. Most buildings in this region were built in 1974 and are Class B.