Most listings are in the $20's per square foot per year. The Poway submarket is going through a an increase in rates. In the last 3 months, the median rate went up $29 per sqft per year.
Compared to the rest of the San Diego market, the Poway submarket has lower rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 25 listings have been made available, which means leases most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 100% of the office spaces in the Poway are subleases, so you might be able to snag a great spot on a short term. 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 1,600 sqft. Most properties in this region are around 1 stories. Most buildings in this market were built in 1999 and are Class B.