On average, listings lease in the $20's per square foot per year. The Oceanside submarket is seeing a an increase in rates. In the last 3 months, the median rate rose $3 per sqft per year. That's a 13% increase in rent.
Compared to the rest of the San Diego market, the Oceanside region has less expensive rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 14 listings have come on the market, which means new listings are probably leasing quickly. You'll want to be prepared to make an offer immediately. About 7% of the available space in the Oceanside are subleases, so you will probably have to focus your search on direct office leases. 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 1,680 sqft. Most properties in this market are close to 2 stories. Most buildings in this area were built in 1984 and are Class B.